Air source heat pump system and method of use for industrial steam generation

ABSTRACT

A system for generating steam for industrial heat. The system may include a plurality of heat pump cycles in thermal communication with each other and in thermal communication with a steam generation cycle. The plurality of heat pump cycles may include first and second heat pump cycles. The first heat pump circulates a first a working fluid and includes a first heat exchanger. The second heat pump cycle circulates a second working fluid and includes a second heat exchanger. The first heat exchanger transfers heat from the first to the second working fluid. The second heat exchanger transfers heat to a third working fluid in the steam generation cycle.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/US22/72937, filed Jun. 14, 2022, which claims the benefit ofU.S. Provisional Application No. 63/211,297, filed Jun. 16, 2021, andU.S. Provisional Application No. 63/290,784, filed Dec. 17, 2021, eachof which is hereby incorporated by reference in its entirety into thepresent application.

FIELD OF THE INVENTION

The present disclosure is directed to industrial steam production. Morespecifically, the present disclosure is directed to a high efficiencyair source heat pump for industrial steam production and methods of usethereof.

BACKGROUND OF THE INVENTION

In the United States, the industrial sector accounts for 22% ofgreenhouse gas emissions, which equals approximately 1.5 gigatonnes ofequivalent carbon dioxide per year (GtCO2e/year). Within the industrialsector, steam production for process heat is one of the largest energyconsumers, accounting for almost 4 quads of U.S. primary energyconsumption and emitting more than 200 MMtonnes of carbon dioxide (CO2)every year. Most of these emissions are generated from burning of fuelsfor conventional boilers, cogeneration, and process heating.

Accordingly, there is a need in the art for systems and methods of steamgeneration for industrial heat that are more efficient and generate lesscarbon emissions. It is with these thoughts in mind, among others, thatthe air source heat pump system and method of use for industrial steamgeneration was developed.

SUMMARY

Aspects of the present disclosure include a system for generating steam.The system may include a first heat pump cycle and a second heat pumpcycle. The first heat pump cycle is configured to circulate a firstworking fluid. The first heat pump cycle may include: first heatexchanger, a first compressor, a second heat exchanger, and a firstexpansion valve. The first heat exchanger is in fluid communication withthe first expansion valve and configured to receive the first workingfluid from the first expansion valve. The first working fluid absorbingheat in the first heat exchanger. The first compressor is in fluidcommunication with the first heat exchanger and configured to receivethe first working fluid from the first exchanger. The first compressoris configured to increase the pressure and temperature of the firstworking fluid. The second heat exchanger is in fluid communication withthe first compressor and configured to receive the first working fluidfrom the first compressor. The second heat exchanger is configured toreject heat from the first working fluid to a second working fluid ofthe second heat pump cycle. The first expansion valve is in fluidcommunication with the second heat exchanger and is configured toreceive the first working fluid from the second heat exchanger. Thefirst expansion valve is configured to expand the first working fluid toa lower pressure.

The second heat pump cycle is configured to circulate the second workingfluid. The second heat pump cycle may include: the second heatexchanger, a second compressor, a third heat exchanger, and a secondexpansion valve. The second heat exchanger is in fluid communicationwith a second expansion valve and is configured to receive the secondworking fluid from the second expansion valve. The second working fluidabsorbing heat from the first working fluid in the second heatexchanger. The second compressor is in fluid communication with thesecond heat exchanger and is configured to receive the second workingfluid from the second heat exchanger. The second compressor isconfigured to increase the pressure and temperature of the secondworking fluid. The third heat exchanger is in fluid communication withthe second compressor and is configured to receive the second workingfluid from the second compressor. The third heat exchanger is in fluidcommunication with a third working fluid in a steam generation system.The third heat exchanger is configured to reject heat from the secondworking fluid to the third working fluid in the steam generation system,the third working fluid being water. The second expansion valve is influid communication with the third heat exchanger and configured toreceive the second working fluid from the third heat exchanger. Thesecond expansion valve configured to expand the second working fluid toa lower pressure.

In certain instances, the system further may include: a firstsuction-line heat exchanger and a second suction-line heat exchanger.The first suction-line heat exchanger is in fluid communication with andbetween the first heat exchanger and the first compressor. The firstsuction-line heat exchanger in fluid communication with and between thesecond heat exchanger and the first expansion valve. The firstsuction-line heat exchanger configured to preheat the first workingfluid prior to compressing the first working fluid with the outflow ofthe first working fluid from the second heat exchanger. The secondsuction-line heat exchanger in fluid communication with and between thesecond heat exchanger and the second compressor. The second suction-lineheat exchanger in fluid communication with and between the third heatexchanger and the second expansion valve. The second suction-line heatexchanger configured to preheat the second working fluid prior tocompressing the second working fluid with the outflow of the secondworking fluid from the third heat exchanger.

In certain instances, the first heat exchanger facilitates heat transferfrom a first transfer fluid to the first working fluid, the first fluidbeing air.

In certain instances, the steam generation system may include a steamcompressor in fluid communication with the third heat exchanger, thesteam compressor configured to increase the pressure and temperature ofthe third working fluid so as to output steam. In certain instances, thesystem further may include the steam generation system.

In certain instances, the steam compressor may be configured to deliversteam at temperatures of greater than or equal to 120 degrees Celsiusfrom heat delivered from the first and second heat pump cycles.

In certain instances, the system further may include a control system inelectrical communication with the first and second heat pump cycles, thecontrol system configured to control the delivery of heat to the thirdworking fluid from at least one or both of a first heat source, and asecond heat source, the first heat source including the first and secondheat pump cycles, the second heat source including an alternate heatsource.

In certain instances, the first and second compressors are centrifugalcompressors. In certain instances, the first and second compressor areelectrically powered.

In certain instances, the first working fluid may be one of afluorocarbon, a hydrofluoroolefin, a hydrofluoroether, a hydrocarbon,carbon dioxide, ammonia, or water, and the second working fluid may beone of a fluorocarbon, a hydrofluoroolefin, a hydrofluoroether, ahydrocarbon, carbon dioxide, ammonia, or water.

Aspects of the present disclosure include a system for generating steamfor industrial heat. The system may include a first heat pump cycle anda second heat pump cycle. The first heat pump cycle configured tocirculate a first working fluid. The first heat pump cycle may include:an evaporator, a first compressor, a heat exchanger, and a firstexpansion valve. The evaporator is in fluid communication with the firstexpansion valve and configured to receive the first working fluid fromthe first expansion valve. The first working fluid absorbing heat in theevaporator. The first compressor is in fluid communication with theevaporator and configured to receive the first working fluid from theevaporator. The first compressor configured to increase the pressure andtemperature of the first working fluid. The heat exchanger in fluidcommunication with the first compressor and configured to receive thefirst working fluid from the first compressor. The heat exchangerconfigured to reject heat from the first working fluid to a secondworking fluid of the second heat pump cycle. The first expansion valvein fluid communication with the heat exchanger and configured to receivethe first working fluid from the heat exchanger, the first expansionvalve configured to expand the first working fluid to a lower pressure.

The second heat pump cycle configured to circulate the second workingfluid. The second heat pump cycle may include: the heat exchanger,suction-line heat exchanger, a second compressor, a steam generator, anda second expansion valve. The heat exchanger in fluid communication witha second expansion valve and configured to receive the second workingfluid from the second expansion valve. The second working fluidabsorbing heat from the first working fluid in the heat exchanger. Thesuction-line heat exchanger in fluid communication with the heatexchanger and configured to receive the second working fluid from theheat exchanger. The suction-line heat exchanger configured to preheatthe second working fluid prior to compressing the second working fluid.The second compressor in fluid communication with the suction-line heatexchanger and configured to receive the second-working fluid from thesuction-line heat exchanger. The second compressor configured toincrease the pressure and temperature of the second working fluid. Thesteam generator in fluid communication with the second compressor andconfigured to receive the second working fluid from the secondcompressor. The steam generator configured to reject heat from thesecond working fluid to a transfer fluid. The suction-line heatexchanger in fluid communication with the steam generator. The secondexpansion valve in fluid communication with the suction-line heatexchanger and configured to receive the second working fluid from thesuction-line heat exchanger. The second expansion valve configured toexpand the second working fluid to a lower pressure.

In certain instances, the system further may include: a third compressorand a fourth compressor. The third compressor in the first heat pumpcycle. The third compressor in fluid communication with and positionedbetween the first compressor and the heat exchanger. The thirdcompressor configured to receive the first working fluid from the firstcompressor. The third compressor configured to increase the pressure andtemperature of the first working fluid. The fourth compressor in thesecond heat pump cycle. The fourth compressor in fluid communicationwith the second compressor and configured to receive the second-workingfluid from the second compressor. The fourth compressor configured toincrease the pressure and temperature of the second working fluid.

In certain instances, the first compressor and third compressor arerotatably coupled together on a shaft and electrically powered by amotor. In certain instances, the second compressor may be electricallypowered by a first motor and the fourth compressor may be electricallypowered by a second motor.

In certain instances, the first heat pump cycle includes a firsteconomizer and a third expansion valve, the first economizer configuredto receive a primary fluid stream of the first working fluid from theheat exchanger and reject heat therefrom in the first economizer, thethird expansion valve configured to receive a secondary fluid stream ofthe first working fluid from the heat exchanger and expand the secondaryfluid stream of the first working fluid to a lower pressure prior toentering the first economizer, the secondary fluid stream of the firstworking fluid configured to absorb heat in the first economizer, whereinthe secondary fluid stream of the first working fluid may be directed toan inflow of the third compressor, and wherein the primary fluid streamof the first working fluid may be directed to an inflow of the firstexpansion valve.

In certain instances, the first compressor in configured to receive theprimary fluid stream of the first working fluid and the secondcompressor may be configured to receive the primary and secondary fluidstreams of the first working fluid.

In certain instances, the second heat pump cycle includes a secondeconomizer and a fourth expansion valve, the second economizerconfigured to receive a primary fluid stream of the second working fluidfrom the steam generator and reject heat therefrom in the secondeconomizer, the fourth expansion valve configured to receive a secondaryfluid stream of the second working fluid from the steam generator andexpand the secondary fluid stream of the second working fluid to a lowerpressure prior to entering the second economizer, the secondary fluidstream of the second working fluid configured to absorb heat in thesecond economizer, wherein the secondary fluid stream of the secondworking fluid may be directed to an inflow of the fourth compressor, andwherein the primary fluid stream of the second working fluid may bedirected to the suction-line heat exchanger to preheat the secondworking fluid exiting the heat exchanger.

In certain instances, the third compressor may be configured to receivethe primary fluid stream of the second working fluid and the fourthcompressor may be configured to receive the primary and secondary fluidstreams of the second working fluid.

In certain instances, the steam generator may be configured to deliversteam at temperatures of greater than or equal to 150 degrees Celsius.

In certain instances, the evaporator may be configured to receive afirst transfer fluid, the evaporator configured to reject heat from thefirst transfer fluid, wherein the first transfer fluid may be air.

Aspects of the present disclosure include a method for generating steamfor industrial heat. The method may include: rejecting heat from a firstcirculating fluid to a first working fluid in a first heat exchanger;preheating the first working fluid in a first suction-line heatexchanger prior to compressing the first working fluid; compressing thefirst working fluid via a first compressor, thereby increasing thepressure of the first working fluid; rejecting heat from the firstworking fluid to a second working fluid in a second heat exchanger;expanding the first working fluid to a lower pressure via a firstexpansion valve; preheating the second working fluid in a secondsuction-line heat exchanger prior to compressing the second workingfluid; compressing the second working fluid via a second compressor,thereby increasing the pressure of the second working fluid; rejectingheat from the second working fluid to a third working in a third heatexchanger, the third working fluid being part of a steam generationsystem; and expanding the second working fluid to a lower pressure via asecond expansion valve.

In certain instances, the steam generation system includes a steamcompressor configured to generate steam from the third working fluid. Incertain instances, the steam compressor may be configured to deliversteam at temperatures of greater than or equal to 120 degrees Celsius.In certain instances, the first and second compressors are centrifugalcompressors. In certain instances, the first and second compressor areelectrically powered.

Aspects of the present disclosure include a method for generating steamfor industrial heat. The method may include: absorbing heat in a firstworking fluid in an evaporator, the first working fluid circulating in afirst heat pump cycle; compressing the first working fluid in a firstcompressor, thereby increasing the pressure of the first working fluid;compressing the first working fluid in a second compressor, therebyincreasing the pressure of the first working fluid; rejecting heat fromthe first working fluid to a second working fluid in a heat exchanger,the second working fluid circulating in a second heat pump cycle;expanding the first working fluid to a lower pressure via a firstexpansion valve; preheating the second working fluid in a suction-lineheat exchanger prior to compressing the second working fluid in a thirdcompressor; compressing the second working fluid in the thirdcompressor, thereby increasing the pressure of the second working fluid;compressing the second working fluid in a fourth compressor, therebyincreasing the pressure of the second working fluid; rejecting heat fromthe second working fluid in a steam generator; rejecting heat from thesecond working fluid in the suction-line heat exchanger after exitingthe steam generator; and expanding the second working fluid to a lowerpressure via a second expansion valve.

In certain instances, the system further may include splitting the firstworking fluid into a primary fluid stream and a secondary fluid stream;expanding the secondary fluid stream of the first working fluid to alower pressure via a third expansion valve, and absorbing heat in thesecondary fluid stream of the first working fluid in first economizer;and rejecting heat from the primary fluid stream of the first workingfluid to the secondary fluid stream of the first working fluid in thefirst economizer.

In certain instances, the system further may include directing theprimary fluid stream of the first working fluid to the first expansionvalve; and directing the secondary fluid stream of the first workingfluid to an inflow of the second compressor.

In certain instances, the first and second compressors are rotatablycoupled together via a shaft and are powered by a motor.

In certain instances, heat may be absorbed in the evaporator fromambient air, and the steam generator may be configured to deliver steamat 150 degrees Celsius or greater.

Aspects of the present disclosure include a system for generating steamfor industrial heat. The system may include a plurality of heat pumpcycles in thermal communication with each other and in thermalcommunication with a steam generation cycle. The plurality of heat pumpcycles may include a first heat pump cycle and a second heat pump cycle.The first heat pump configured to circulate a first a working fluid andincluding a first heat exchanger and a first suction-line heatexchanger. The second heat pump cycle configured to circulate a secondworking fluid and including a second heat exchanger and a secondsuction-line heat exchanger. The first suction-line heat exchangerconfigured to preheat the first working fluid prior to compressing thefirst working fluid. The first heat exchanger configured to transferheat from the first working fluid to the second working fluid. Thesecond suction-line heat exchanger configured to preheat the secondworking fluid prior to compressing the second working fluid. The secondheat exchanger configured to transfer heat from the second working fluida third working fluid in the steam generation cycle.

Aspects of the present disclosure include an energy arbitrage systemincluding a cascading heat pump system that generates steam. The energyarbitrage system further includes a computing device in communicationwith the cascading heat pump system for generating steam and with aboiler configured to generate steam. The computing device includes aprocessing device and a computer-readable medium with one or moreexecutable instructions stored thereon, wherein the processing device ofthe computing device executes the one or more instructions to performthe operations of: receive steam demands from a facility; sendinstructions to the cascading heat pump system for generating steam toprovide for the steam demands from the facility; send instructions tothe boiler to provide for a remaining portion of the steam demands fromthe facility if the cascading heat pump system for generating steamcannot fulfill all of the steam demands.

In certain instances, the computing device is in further communicationwith a renewable energy source configured to provide electricity to theelectric grid and to the cascading heat pump system. The processingdevice of the computing device executes the one or more instructions toperform the further operations of: receive information associated withan amount of electricity produced by the renewable energy source; sendinstructions to the renewable energy source to supply electricity to thesystem for generating steam; send instructions to the renewable energysource to supply excess electricity that is not required by thecascading heat pump system for generating steam to the electric grid;and send instructions to the cascading heat pump system for generatingsteam to draw electricity from the electric grid if the renewable energysource supplies an insufficient amount of electricity.

Aspects of the present disclosure include an energy arbitrage systemincluding a cascading heat pump system that generates steam. The energyarbitrage system further includes a computing device in communicationwith the cascading heat pump system for generating steam and with arenewable energy source configured to provide electricity to theelectric grid and to the system for generating steam. The computingdevice includes a processing device and a computer-readable medium withone or more executable instructions stored thereon, wherein theprocessing device of the computing device executes the one or moreinstructions to perform the operations of: receive informationassociated with an amount of electricity produced by the renewableenergy source; send instructions to the renewable energy source tosupply electricity to the system for generating steam; send instructionsto the renewable energy source to supply excess electricity that is notrequired by the cascading heat pump system for generating steam to theelectric grid; and send instructions to the cascading heat pump systemfor generating steam to draw electricity from the electric grid if therenewable energy source supplies an insufficient amount of electricity.

Aspects of the present disclosure include an energy arbitrage systemincluding a cascading heat pump system that generates steam. The energyarbitrage system further includes a computing device in communicationwith: the system for generating steam; a thermal storage unit configuredto deliver steam; and a renewable energy source configured to provideelectricity to the thermal storage unit and to the system for generatingsteam. The computing device includes a processing device and acomputer-readable medium with one or more executable instructions storedthereon, wherein the processing device of the computing device executesthe one or more instructions to perform the operations of: receiveinformation associated with an amount of electricity produced by therenewable energy source; send instructions to the renewable energysource to supply electricity to the system for generating steam; andsend instructions to the renewable energy source to supply excesselectricity that is not required by the cascading heat pump system forgenerating steam to the thermal storage unit.

In certain instances, the processing device of the computing deviceexecutes the one or more instructions to perform the further operationsof: when the amount of electricity produced by the renewable energysource is insufficient to operate the system for generating steam, sendinstructions to the thermal storage units to supply steam to thefacility.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a modular, electric-powered, cascading,air-source heat pump system in use with a steam compressor for use inindustrial applications.

FIG. 2 is a diagram of the cascading heat pump system, comprising a lowtemperature air source heat pump and a high temperature steam coupledheat pump, and a steam compressor.

FIG. 3 is a diagrammatic view of a steam generation system comprising abottoming heat pump cycle, a topping heat pump cycle, and a steamcompressor.

FIG. 4 is a diagram of a modular, cascading, air-source heat pumpsystem.

FIG. 5 is a diagram of the cascading heat pump system, comprising a lowtemperature air source heat pump and a high temperature stream coupledheat pump.

FIG. 6 is a table that includes exemplar design specification for atwo-stage compressor for the bottom cycle.

FIG. 7 is a diagram of a design for a two-stage compressor for thetopping cycle.

FIG. 8 is a table that includes exemplar design specification for atwo-stage compressor for the topping cycle.

FIG. 9 is a diagram of the electric power input and thermal poweroutput.

FIG. 10 is a diagrammatic view of a steam generation system comprising abottoming heat pump cycle and a topping heat pump cycle, with aneconomizer and suction-line heat exchangers.

FIG. 11 is a diagram of an energy arbitrage system.

FIG. 12 is an exemplary diagram of a computing device capable ofoperating as a control system in the energy arbitrage system.

DETAILED DESCRIPTION

It will be appreciated that for simplicity and clarity of illustration,where appropriate, reference numerals have been repeated among thedifferent figures to indicate corresponding or analogous elements. Inaddition, numerous specific details are set forth in order to provide athorough understanding of the embodiments described herein. However, itwill be understood by those of ordinary skill in the art that theembodiments described herein can be practiced without these specificdetails. In other instances, methods, procedures and components have notbeen described in detail so as not to obscure the related relevantfeature being described. The drawings are not necessarily to scale andthe proportions of certain parts may be exaggerated to better illustratedetails and features. The description is not to be considered aslimiting the scope of the embodiments described herein. As such,elements of one system can be incorporated into any of the systemsdescribed herein. And, elements can be subtracted from any of thesystems described herein without limitation.

Several definitions that apply throughout this disclosure will now bepresented.

The term “conduit” is defined as a tube, pipe, or channel to conveychannel, or otherwise flow fluid. The conduit may be a system conduit ormay connect two elements within the system, thereby establishing fluidcommunication between the two elements.

The term “coupled” is defined as connected, whether directly, orindirectly, through intervening components, and is not necessarilylimited to physical connections. The connection can be such that theobjects are permanently or releasably connected.

FIG. 1 illustrates an exemplary steam generation system 100 in anindustrial application. A specific example of the components of such asystem will be shown and described in more detail in reference to FIG. 3. FIG. 1 provides an overview of the system 100, which includes atwo-stage air-source heat pump comprising a bottoming heat pump 102(i.e., a first heat pump) and a topping heat pump 104 (i.e., a secondheat pump) that are thermally coupled together by an intermediate heatexchanger (i.e., a heat exchanger). The steam generation system 100 mayalso include a steam compressor 106. In the intermediate heat exchanger,the working fluid in the bottoming heat pump 102 rejects heat to theworking fluid in the topping heat pump 104. Then, in a steam generator(i.e., a heat exchanger) the working fluid of the topping heat pump 104rejects heat to a third working fluid 108. In some instances, the thirdworking fluid 108 may pass through a steam compressor 106 afterabsorbing heat from steam generator.

Each of the heat pumps 102, 104 are used to “pump” lower temperatureheat to a higher temperature by using an electrical energy source.Currently available heat pumps either do not generate a large enoughtemperature lift to produce steam or they require the use of a highertemperature waste heat stream as the energy source. As described herein,the system 100 utilizes a “cascading” or series of heat pump cycles inthermal connection with each other that progressively raise thetemperatures to deliver decarbonized steam at a lower cost thanalternative sources. The system 100 does not require waste heat todeliver high temperature steam.

The steam generation system 100 of FIG. 1 may be generally applicable toa variety of industrial processes and/or manufacturing environments. Forexample, the steam generation system 100 may be used to generateindustrial steam. In one instance, the bottoming heat pump 102 and thetopping heat pump 104 may be modular, electric-powered air-source heatpumps arranged in a thermally cascading manner. This modularity mayenable industry-specific needs, such as different steam pressures andcapacities. While the systems in this application illustrate two heatpump cycles (i.e., topping heat pump and bottoming heat pump), thesystem is scalable and can be modified to include additional heat pumps.In certain instances, the system may include three heat pump cycles. Incertain instances, the system may include four heat pump cycles. Incertain instances, the system may include five heat pump cycles. In oneinstance, the steam generation system 100 may generate steam at atemperature of approximately 150-degrees Celsius and at a pressure ofapproximately 4.5 bar, which may satisfy a majority of industrial steamproduction needs including the food, paper, and chemical industries.

In the steam generation system 100 of FIG. 1 , the bottoming heat pump102 may utilize ambient air as a heat source (i.e., air sourced). Theevaporator (i.e., heat exchanger) of the bottoming heat pump 102captures heat from the ambient air. The heat is absorbed by theevaporator of the bottoming heat pump 102, thereby evaporating theworking fluid within the bottoming heat pump 102.

The topping heat pump 104 is thermally coupled to the bottoming heatpump 102 by an intermediate heat exchanger. In one instance, theintermediate heat exchanger comprises the condenser of the bottomingheat pump 102 and the evaporator of the topping heat pump 104. Thus,within the intermediate heat exchanger, the condenser of the bottomingheat pump 102 rejects heat and the evaporator of the topping heat pump104 absorbs heat.

The conduit (i.e., fluid flow path) for a third working fluid 108 iscoupled to the topping heat pump 104 by a steam generator (i.e., heatexchanger). In one instance, the steam generator comprises the condenserof the topping heat pump 104 and the conduit for a third working fluid108. Thus, within the steam generator, the condenser of the topping heatpump 104 rejects heat and the third working fluid 108 absorbs heat.

Before entering the steam generator, a mechanical pump may be used toincrease the pressure of the third working fluid 108. After the thirdworking fluid 108 exits the steam generator, a steam compressor 106 maybe used to increase the pressure and the temperature of the thirdworking fluid 108. Thus, a mechanical pump may be installed before thesteam generator, a steam compressor 106 may be installed after the steamgenerator, or both.

In one instance, the third working fluid 108 is water. Within the steamgenerator, the water absorbs heat from the working fluid of the toppingheat pump 104. In one example, the pressure of the water may be greaterthan or equal to the target steam saturation temperature. In otherwords, the water may absorb sufficient heat from the topping heat pump104 to evaporate into steam 110. After the steam generator, a steamcompressor 106 may be used to directly increase the pressure andtemperature of the steam 110. In one example, the pressure of the watermay be less than the target steam saturation temperature after exitingthe steam generator and, therefore, the steam compressor 106 may be usedto increase the pressure of the water to the required saturationtemperature. The system 100 may be retrofitted to existing steamgeneration systems within facilities. Alternatively, the system 100 mayinclude a steam generation system as part of the overall system 100.

The steam generation system 100 may be powered by electricity 112. Inother words, electricity 112 is input into the steam generation system100 in order to generate steam 110. For example, the steam generationsystem 100 may be powered through grid electricity, onsite renewableenergy, or a combination thereof. The steam generation system 100 mayenable economic decarbonization of industrial steam production, as steamenergy in the industrial sector 114 accounts for almost 4 quads of U.S.primary energy consumption and emits more than 200 MMtonne of CO2 everyyear.

In some instances, the steam generation system 100 may incorporateenergy arbitrage. In other words, energy arbitrage may be used inconjunction with the steam generation system 100 by incorporatingadditional systems that can provide heating to the steam generationsystem 100 and/or provide electricity to the heat pump systems describedherein. The additional systems could include solar arrays, thermalstorage systems, and fuel boilers (e.g., natural gas, coal, wasteproducts, or biomass), among other systems. These systems can be coupledto the steam generation system 100 and/or the heat pump systems andselectively actuated to provide heat to the system 100 and/orelectricity to the heat pump systems. The specific system that providesheat to the steam generation system 100 and/or electricity to the heatpump systems can be determined by the availability, and price of theenergy source of the system applying heat or electricity, as well asother factors including the requirements of the steam generation system100. By incorporating energy arbitrage, the steam generation system 100is capable of generating consistent steam delivery while significantlyreducing carbon emissions.

In some instances, the steam generation system 100 may include more thantwo heat pumps arranged in a thermal cascading manner to heat pump airto generate steam. In one instance, the steam generation system 100 mayinclude three heat pumps. For example, the steam generation system 100may include a bottoming heat pump (i.e., a first heat pump), anintermediate heat pump (i.e., a second heat pump), and a topping heatpump (i.e., a third heat pump). In another instance, the steamgeneration system 100 may include four heat pumps. For example, thesteam generation system 100 may include a bottoming heat pump (i.e., afirst heat pump), a first intermediate heat pump (i.e., a second heatpump), a second intermediate heat pump (i.e., a third heat pump), and atopping heat pump (i.e., a fourth heat pump). In another instance, thesteam generation system 100 may include five heat pumps.

In one instance, the bottoming heat pump 102 is coupled to the ambientair (i.e., air sourced). However, in other instances, the bottoming heatpump 102 may be coupled to another low temperature heat source. Forexample, the low temperature heat source could be a liquid loop thatrejects heat to the air, the ground, or another co-located cooling load.In one example, the liquid loop may contain water.

FIG. 2 illustrates a partial diagram of a steam generation system 200,which is a partial embodiment of the steam generation system 100illustrated in FIG. 1 . The steam generation system 200 includes abottoming heat pump 202 (i.e., a first heat pump) and a topping heatpump 204 (i.e., a second heat pump) arranged in a thermally cascadingmanner. The bottoming heat pump 202 may be a low temperature air sourceheat pump and the topping heat pump 204 may be a high temperature steamcoupled heat pump. The steam generation system 200 may also include asteam compressor 206.

The steam generation system 200 may include cascading heat pumps thatincorporate high-efficiency components to achieves a coefficient ofperformance greater than two without using waste heat. For example,high-efficiency components may include high-efficiency refrigerantcompressors and motors. In one instance, the compressors may be equal toor greater than 85% efficient and the motors may be equal to or greaterthan 93% efficient.

For example, a 1 thermal megawatt (MWth) steam generation system 200 mayproduce 150-degree Celsius steam at a nominal ambient temperature of20-degrees Celsius. In other words, the steam generation system 200 mayprovide a temperature lift from 20-degrees Celsius to 150-degreesCelsius at a coefficient of performance greater than two withoutrequiring waste heat.

Heat transfer 216 a involves the bottoming heat pump 202 capturing heatfrom the ambient air by evaporating a working fluid, which may be arefrigerant. In one instance, the ambient air may be approximately20-degrees Celsius, and the working fluid may be evaporated at 0-degreesCelsius. Electricity 212 a may be applied to the bottoming heat pump202, which may include a 144 kilowatt-electric (kWe) high efficiencycompressor and motor. In one instance, the compressor may operate atapproximately 85% efficiency and the motor may operate at approximately93% efficiency.

Heat transfer 216 b involves the condenser from the bottoming heat pump202 rejecting heat to the evaporator in the topping heat pump 204,thereby evaporating the working fluid in the topping heat pump 204. Theworking fluid in the topping heat pump 204 may be a refrigerant. In oneinstance, the working fluid in the topping heat pump 204 may beevaporated at 50-degrees Celsius. Electricity 212 b may be applied tothe topping heat pump 204, which may include a 170 kWe high efficiencycompressor and motor. In one instance, the compressor may operate atapproximately 85% efficiency and the motor may operate at approximately93% efficiency.

Heat transfer 216 c involves the condenser from the topping heat pump204 rejecting heat to an evaporating water stream. Within theevaporating water stream, electricity 212 c may be applied to a steamcompressor 206, which may consume an additional 122 kWe. Thus, 1 MWth ofsteam 210 is delivered at a 150-degrees Celsius saturation temperature.

In colder environments, the steam generation system 200 coefficient ofperformance may decrease due to the higher-pressure lift required by therefrigerant compressors. However, the steam generation system 200 mayachieve high performance even in cold environments through the systemdesign and high efficiency compressors. The steam generation system 200may use two different working fluids, for the topping and bottomingcycles, and a final stage steam compressor. In one instance, reductionsin auxiliary load, increases in motor efficiency, and improved aircoupled heat exchangers may be optimized to decrease the refrigerant toambient air temperature difference. For example, increasing compressorefficiency to 90%, decreasing the evaporator to air temperaturedifference from 20-degrees Celsius to 8.5-degrees Celsius, andincreasing the motor efficiency to 96% allows the steam generationsystem 200 to maintain a coefficient of performance greater than twowhen the ambient air is less than minus 6.5-degrees Celsius.

FIG. 3 illustrates a steam generation system 300 including many of theelements described in reference to FIGS. 1 and 2 . FIG. 3 is adiagrammatic view of the steam generation system 300, which includes afirst heat pump cycle 302 (i.e., a bottoming heat pump cycle) and asecond heat pump cycle 304 (i.e., a topping heat pump cycle) in thermalcommunication with each other. The steam generation system 300 is inthermal communication with the second heat pump cycle 304 and may alsoinclude a steam compressor 306.

The first heat pump cycle 302 circulates a first working fluid 318 via aconduit 320 of the first heat pump cycle 302, as illustrated in FIG. 3 .In one instance, the first working fluid 318 may be a fluorocarbon. Asnonlimiting examples, the fluorocarbon may be R1234ze(z) or R1234ze(E).In one instance, the first working fluid 318 may be a hydrofluoroolefin.As a nonlimiting example, the hydrofluoroolefin may be R514a. In oneinstance, the first working fluid 318 may be a hydrofluoroether. In oneinstance, the first working fluid 318 may be a hydrocarbon. In oneinstance, the first working fluid 318 may be carbon dioxide. In oneinstance, the first working fluid 318 may be ammonia. In one instance,the first working fluid 318 may be water. In one instance, the firstworking fluid 318 may be an engineered fluid. As a nonlimiting example,the engineered fluid may be Novec 649.

In the first heat pump cycle 302, a heat exchanger 322 receives thefirst working fluid 318 from an expansion valve 324. In other words, thefirst working fluid 318 exits the expansion valve 324 at the expansionvalve outlet 326 and enters the heat exchanger 322 at the heat exchangerinlet 328. A conduit 320 connects the expansion valve outlet 326 to theheat exchanger inlet 328, thereby establishing fluid communicationbetween the expansion valve 324 and the heat exchanger 322. In the heatexchanger 322, the first working fluid 318 absorbs heat. This heatabsorption may vaporize the first working fluid 318, whereby the firstworking fluid 318 is a low-pressure vapor when it exits the heatexchanger 322 at the heat exchanger outlet 330. In one instance, theheat exchanger 322 may include the evaporator of the first heat pumpcycle 302, whereby the evaporator absorbs heat and the first workingfluid 318 is evaporated within the evaporator. In one instance, the heatexchanger 322 may be a low-temperature evaporator.

In one instance, a suction-line heat exchanger (“SLHX”) 332 may beincorporated into the first heat pump cycle 302. The SLHX 332 receivesthe first working fluid 318 from the heat exchanger 322 in a firstpassage of the SLHX 332. In other words, the first working fluid 318exits the heat exchanger 322 at the heat exchanger outlet 330 and entersthe SLHX 332 at the SLHX inlet 334. A conduit 320 connects the heatexchanger outlet 330 to the SLHX inlet 334, thereby establishing fluidcommunication between the heat exchanger 322 and the SLHX 332. In thefirst passage of the SLHX 332, the first working fluid 318 absorbs heat,thereby further heating (i.e., preheating) the first working fluid 318before it exits the SLHX 332 at the SLHX outlet 336.

In other instances, the first heat pump cycle 302 does not include theSLHX 332. In other words, the first working fluid 318 exits the heatexchanger 322 at the heat exchanger outlet 330 and enters the compressor338 at the compressor inlet 340. A conduit 320 connects the heatexchanger outlet 330 to the compressor inlet 340, thereby establishingfluid communication between the heat exchanger 322 and the compressor338.

A compressor 338 receives the first working fluid 318 from the SLHX 332.In other words, the first working fluid 318 exits the SLHX 332 at theSLHX outlet 336 and enters the compressor 338 at the compressor inlet340. A conduit 320 connects the SLHX outlet 336 to the compressor inlet340, thereby establishing fluid communication between the SLHX 332 andthe compressor 338. In the compressor 338, the first working fluid 318is compressed to a higher pressure, which increases the temperature,before the first working fluid 318 exits the compressor 338 at thecompressor outlet 342. In one instance, the compressor 338 is ahigh-efficiency compressor. In one instance, the compressor 338 may be acentrifugal compressor. In one instance, the compressor 338 may be atwo-stage centrifugal compressor. In one instance, the compressor 338may be electrically powered. In one instance, a high-speed and/orhigh-efficiency motor may drive the compressor 338.

A heat exchanger 344 (i.e., the intermediate heat exchanger) thermallycouples the first heat pump cycle 302 with the second heat pump cycle304. The heat exchanger 344 receives the first working fluid 318 fromthe compressor 338. In other words, the first working fluid 318 exitsthe compressor 338 at the compressor outlet 342 and enters the heatexchanger 344 at the heat exchanger inlet 346. A conduit 320 connectsthe compressor outlet 342 to the heat exchanger inlet 346, therebyestablishing fluid communication between the compressor 338 and the heatexchanger 344. In the heat exchanger 344, the first working fluid 318rejects heat. This heat rejection may condense the first working fluid318 before it exits the heat exchanger 344 at the heat exchanger outlet348. In one instance, the heat exchanger 344 comprises the condenser ofthe first heat pump cycle 302 and the evaporator of the second heat pumpcycle 304. Thus, within the heat exchanger 344, the condenser of thefirst heat pump cycle 302 rejects heat and the evaporator of the secondheat pump cycle 304 absorbs heat. In the heat exchanger 344, the secondworking fluid 350, which circulates within a conduit 352 within thesecond heat pump cycle 304, absorbs heat. This heat absorption mayvaporize the second working fluid 350, whereby the second working fluid350 is a low-pressure vapor when it exits the heat exchanger 344.

In one instance, when the SLHX 332 is incorporated into the first heatpump cycle 302, the SLHX 332 receives the first working fluid 318 fromthe heat exchanger 344 in a second passage of the SLHX 332. In otherwords, the first working fluid 318 exits the heat exchanger 344 at theheat exchanger outlet 348 and enters the SLHX 332 at the SLHX inlet 354.A conduit 320 connects the heat exchanger outlet 348 to the SLHX inlet354, thereby establishing fluid communication between the heat exchanger344 and the SLHX 332. In the second passage of the SLHX 332, the firstworking fluid 318 rejects heat, thereby cooling (i.e., precooling) thefirst working fluid 318 before it exits the SLHX 332 at the SLHX outlet356.

In other instances, the first heat pump cycle 302 does not include theSLHX 332. In other words, the first working fluid 318 exits the heatexchanger 344 at the heat exchanger outlet 348 and enters the expansionvalve 324 at the expansion valve inlet 358. A conduit 320 connects theheat exchanger outlet 348 to the expansion valve inlet 358, therebyestablishing fluid communication between the heat exchanger 344 and theexpansion valve 324.

An expansion valve 324 receives the first working fluid 318 from theSLHX 332. In other words, the first working fluid 318 exits the SLHX 332at the SLHX outlet 356 and enters the expansion valve 324 at theexpansion valve inlet 358. A conduit 320 connects the SLHX outlet 356 tothe expansion valve inlet 358, thereby establishing fluid communicationbetween the SLHX 332 and the expansion valve 324. In the expansion valve324, the first working fluid 318 is expanded to a lower pressure, whichdecreases the temperature, before the first working fluid 318 exits theexpansion valve 324 at the expansion valve outlet 326.

The second heat pump cycle 304 circulates a second working fluid 350, asillustrated in FIG. 3 . In one instance, the second working fluid 350may be a fluorocarbon. As nonlimiting examples, the fluorocarbon may beR1234ze(z) or R1234ze(E). In one instance, the second working fluid 350may be a hydrofluoroolefin. As a nonlimiting example, thehydrofluoroolefin may be R514a. In one instance, the second workingfluid 350 may be a hydrofluoroether. In one instance, the second workingfluid 350 may be a hydrocarbon. In one instance, the second workingfluid 350 may be carbon dioxide. In one instance, the second workingfluid 350 may be ammonia. In one instance, the second working fluid 350may be water. In one instance, the second working fluid 350 may be anengineered fluid. As a nonlimiting example, the engineered fluid may beNovec 649.

In one instance, the same fluid may be used for both the first workingfluid 318 and the second working fluid 350. In other instances, adifferent fluid may be used for the first working fluid 318 and thesecond working fluid 350.

In one instance, the second heat pump cycle 304 may contain the samecomponents as the first heat pump cycle 302. The components of thesecond heat pump cycle 304 may be arranged in the same configuration asthe components of the first heat pump cycle 302. The components of thesecond heat pump cycle 304 may be arranged in a different configurationthan the components of the first heat pump cycle 302. In otherinstances, the second heat pump cycle 304 may contain differentcomponents than the first heat pump cycle 302.

In the second heat pump cycle 304, a heat exchanger 344 receives thesecond working fluid 350 from an expansion valve 360. In other words,the second working fluid 350 exits the expansion valve 360 at theexpansion valve outlet 362 and enters the heat exchanger 344 at the heatexchanger inlet 364. A conduit 352 connects the expansion valve outlet362 to the heat exchanger inlet 364, thereby establishing fluidcommunication between the expansion valve 360 and the heat exchanger344. In the heat exchanger 344, the second working fluid 350 absorbsheat. This heat absorption may vaporize the second working fluid 350,whereby the second working fluid 350 is a low-pressure vapor when itexits the heat exchanger 344 at the heat exchanger outlet 366. In oneinstance, the heat exchanger 344 comprises the condenser of the firstheat pump cycle 302 and the evaporator of the second heat pump cycle304. Thus, within the heat exchanger 344, the condenser of the firstheat pump cycle 302 rejects heat and the evaporator of the second heatpump cycle 304 absorbs heat.

In one instance, a suction-line heat exchanger (“SLHX”) 368 may beincorporated into the second heat pump cycle 304. The SLHX 368 receivesthe second working fluid 350 from the heat exchanger 344 in a firstpassage of the SLHX 368. In other words, the second working fluid 350exits the heat exchanger 344 at the heat exchanger outlet 366 and entersthe SLHX 368 at the SLHX inlet 370. A conduit 352 connects the heatexchanger outlet 366 to the SLHX inlet 370, thereby establishing fluidcommunication between the heat exchanger 344 and the SLHX 368. In thefirst passage of the SLHX 368, the second working fluid 350 absorbsheat, thereby further heating (i.e., preheating) the second workingfluid 350 before it exits the SLHX 368 at the SLHX outlet 372.

In other instances, the second heat pump cycle 304 does not include theSLHX 368. In other words, the second working fluid 350 exits the heatexchanger 344 at the heat exchanger outlet 366 and enters the compressor374 at the compressor inlet 376. A conduit 352 connects the heatexchanger outlet 366 to the compressor inlet 376, thereby establishingfluid communication between the heat exchanger 344 and the compressor374.

A compressor 374 receives the second working fluid 350 from the SLHX368. In other words, the second working fluid 350 exits the SLHX 368 atthe SLHX outlet 372 and enters the compressor 374 at the compressorinlet 376. A conduit 352 connects the SLHX outlet 372 to the compressorinlet 376, thereby establishing fluid communication between the SLHX 368and the compressor 374. In the compressor 374, the second working fluid350 is compressed to a higher pressure, which increases the temperature,before the second working fluid 350 exits the compressor 374 at thecompressor outlet 378. In one instance, the compressor 374 is ahigh-efficiency compressor. In one instance, the compressor 374 may be acentrifugal compressor. In one instance, the compressor 374 may beelectrically powered. In one instance, a high-speed and/orhigh-efficiency motor may drive the compressor 374.

A heat exchanger 380 thermally couples the second heat pump cycle 304with the system of the third working fluid 308. The heat exchanger 380receives the second working fluid 350 from the compressor 374. In otherwords, the second working fluid 350 exits the compressor 374 at thecompressor outlet 378 and enters the heat exchanger 380 at the heatexchanger inlet 382. A conduit 352 connects the compressor outlet 378 tothe heat exchanger inlet 382, thereby establishing fluid communicationbetween the compressor 374 and the heat exchanger 380. In the heatexchanger 380, the second working fluid 350 rejects heat. This heatrejection may condense the second working fluid 350 before it exits theheat exchanger 380 at the heat exchanger outlet 384. In one instance,the heat exchanger 380 may include the condenser of the second heat pumpcycle 304, whereby the condenser rejects heat and the second workingfluid 350 condenses within the condenser. In the heat exchanger 380, thethird working fluid 308, which may flow within a conduit 386, absorbsheat. This heat absorption may vaporize the third working fluid 308,whereby the third working fluid 308 is steam when it exits the heatexchanger 380.

In one instance, when the SLHX 368 is incorporated into the second heatpump cycle 304, the SLHX 368 receives the second working fluid 350 fromthe heat exchanger 380 in a second passage of the SLHX 368. In otherwords, the second working fluid 350 exits the heat exchanger 380 at theheat exchanger outlet 384 and enters the SLHX 368 at the SLHX inlet 388.A conduit 352 connects the heat exchanger outlet 384 to the SLHX inlet388, thereby establishing fluid communication between the heat exchanger380 and the SLHX 368. In the second passage of the SLHX 368, the secondworking fluid 350 rejects heat, thereby cooling (i.e., precooling) thesecond working fluid 350 before it exits the SLHX 368 at the SLHX outlet390.

In other instances, the second heat pump cycle 304 does not include theSLHX 368. In other words, the second working fluid 350 exits the heatexchanger 380 at the heat exchanger outlet 384 and enters the expansionvalve 360 at the expansion valve inlet 392. A conduit 352 connects theheat exchanger outlet 384 to the expansion valve inlet 392, therebyestablishing fluid communication between the heat exchanger 380 and theexpansion valve 360.

An expansion valve 360 receives the second working fluid 350 from theSLHX 368. In other words, the second working fluid 350 exits the SLHX368 at the SLHX outlet 390 and enters the expansion valve 360 at theexpansion valve inlet 392. A conduit 352 connects the SLHX outlet 390 tothe expansion valve inlet 392, thereby establishing fluid communicationbetween the SLHX 368 and the expansion valve 360. In the expansion valve360, the second working fluid 350 is expanded to a lower pressure, whichdecreases the temperature, before the second working fluid 350 exits theexpansion valve 360 at the expansion valve outlet 362.

A third working fluid 308 may absorb heat from the heat exchanger 380,as illustrated in FIG. 3 . In other words, the heat exchanger 380 mayreceive the third working fluid 308. Within the heat exchanger 380, thesecond working fluid 350 rejects heat and the third working fluid 308absorbs heat. In one instance, the heat exchanger 380 may include thecondenser of the second heat pump cycle 304, whereby the condenserrejects heat and the third working fluid 308 absorbs heat. The secondworking fluid 350 is condensed as it rejects heat within the condenser.In one instance, the heat exchanger 380 may be a steam generator. Withinthe steam generator, the third working fluid 308 may absorb sufficientheat to vaporize.

In one instance, the third working fluid 308 may be supplied to the heatexchanger 380 via a conduit 386. In other words, the conduit 386 for thethird working fluid 308 is thermally coupled to the second heat pumpcycle 304 by the heat exchanger 380.

In one instance, a mechanical pump 301 may increase the pressure of thethird working fluid 308. The mechanical pump 301 may be upstream fromthe heat exchanger 380, whereby the heat exchanger 380 receives thethird working fluid 308 from the mechanical pump 301. In other words,the third working fluid 308 exits the mechanical pump 301 at themechanical pump outlet 303 and enters the heat exchanger 380 at a heatexchanger inlet 305. A conduit 386 connects the mechanical pump outlet303 to the heat exchanger inlet 305, thereby establishing fluidcommunication between the mechanical pump 301 and the heat exchanger380. The third working fluid 308 exits the heat exchanger 380 at a heatexchanger outlet 307 and may enter a conduit 386.

In one instance, a steam compressor 306 may increases the pressure andtemperature of the third working fluid 308. The steam compressor 306 maybe downstream from the heat exchanger 380, whereby the steam compressor306 receives the third working fluid 308 from the heat exchanger 380. Inother words, the third working fluid 308 exits the heat exchanger 380 atthe heat exchanger outlet 307 and enters the steam compressor 306 at thesteam compressor inlet 309. A conduit 386 connects the heat exchangeroutlet 307 to the steam compressor inlet 309, thereby establishing fluidcommunication between the heat exchanger 380 and the steam compressor306.

In the steam compressor 306, the third working fluid 308 is compressedto a higher pressure and temperature. In one instance, the steamcompressor 306 increases the pressure and temperature of the thirdworking fluid 308 to turn the third working fluid 308 into steam beforethe third working fluid 308 exits the steam compressor 306 at the steamcompressor outlet 311. The steam may enter a conduit 386 connected tothe steam compressor outlet 311. In one instance, the steam compressor306 delivers steam at a temperature equal to or greater than 120 degreesCelsius. In one instance, the steam compressor 306 is a high-efficiencycompressor. In one instance, the steam compressor 306 may be acentrifugal compressor. In one instance, the steam compressor 306 may beelectrically powered.

In one instance, the third working fluid 308 is water. Within the heatexchanger 380, the water absorbs heat from the second working fluid 350of the second heat pump cycle 304. In one example, the pressure of thewater may be greater than or equal to the target steam saturationtemperature when the water exits the heat exchanger 380 at the heatexchanger outlet 307. In other words, the water may absorb sufficientheat from the second heat pump cycle 304 to evaporate into steam. Afterthe heat exchanger 380, a steam compressor 306 may be used to directlyincrease the pressure and temperature of the steam. In one example, thepressure of the water may be less than the target steam saturationtemperature when the water exits the heat exchanger 380 at the heatexchanger outlet 307. Therefore, the steam compressor 306 may be used toincrease the pressure of the water to the required saturationtemperature.

Turning back to the first heat pump cycle 302 and the heating for it, atransfer fluid 313 may reject heat to the heat exchanger 322, asillustrated in FIG. 3 . In other words, the heat exchanger 322 receivesthe transfer fluid 313. Within the heat exchanger 322, the transferfluid 313 rejects heat and the first working fluid 318 absorbs heat. Inone instance, the heat exchanger 322 may include the evaporator of thefirst heat pump cycle 302, whereby the transfer fluid 313 rejects heatand the evaporator absorbs heat. The first working fluid 318 isevaporated as it absorbs heat within the evaporator. In one instance,the heat exchanger 322 may be a low-temperature evaporator.

In one instance, the transfer fluid 313 may be supplied to the heatexchanger 322 via a conduit 315. In other words, the conduit 315 for thetransfer fluid 313 is coupled to the first heat pump cycle 302 by theheat exchanger 322.

In one instance, a mechanical pump 317 may increase the pressure of thetransfer fluid 313. The mechanical pump 317 may be upstream from theheat exchanger 322, whereby the heat exchanger 322 receives the transferfluid 313 from the mechanical pump 317. In other words, the transferfluid 313 exits the mechanical pump 317 at the mechanical pump outlet319 and enters the heat exchanger 322 at a heat exchanger inlet 321. Aconduit 315 connects the mechanical pump outlet 319 to the heatexchanger inlet 321, thereby establishing fluid communication betweenthe mechanical pump 317 and the heat exchanger 322. The transfer fluid313 exits the heat exchanger 322 at a heat exchanger outlet 323 and mayenter a conduit 315.

In one instance, the transfer fluid 313 is ambient air, whereby the heatexchanger 322 of the first heat pump cycle 302 utilizes ambient air as aheat source (i.e., air sourced). The heat exchanger 322 of the firstheat pump cycle 302 may capture heat from the ambient air. The heat isabsorbed by the heat exchanger 322 of the first heat pump cycle 302,thereby evaporating the first working fluid 318 within the first heatpump cycle 302.

In other instances, the transfer fluid 313 may be liquid that isconnected to a low temperature heat source. In one instance, the lowtemperature heat source may be ambient air. In other instances, thefirst heat pump cycle 302 may be coupled to another low temperature heatsource. For example, the low temperature heat source could be a liquidloop that rejects heat to the air, the ground, or another co-locatedcooling load. In one example, the liquid loop may contain water.

A control system may be in electrical communication with the first heatpump cycle 302 and the second heat pump cycle 304. The control systemmay control the delivery of heat from a first heat source and/or asecond heat source to the third working fluid 308. The first heat sourcemay include the first heat pump cycle 302 and the second heat pump cycle304. The second heat source may include an alternate heat source such asa thermal storage steam system, a fuel boiler (e.g., natural gas, coal,biomass), among other possible heat sources. The control system may alsocontrol the source of electrical power supplied to the first and secondheat pump cycles 302, 304. For instance, the first and second heat pumpcycles 302, 304 may be electrically coupled to the electrical grid and asolar grid. When conditions are favorable based on availability, price,and output needs, the first and second heat pump cycles 302, 304 may besupplied power from one or both of the electrical grid and the solargrid.

FIG. 4 illustrates an exemplary steam generation system 400 in anindustrial application. A specific example of the components of such asystem will be shown and described in more detail in reference to FIG.10 . FIG. 4 provides an overview of the system 400, which includes atwo-stage air-source heat pump comprising a bottoming heat pump 402(i.e., a first heat pump) and a topping heat pump 404 (i.e., a secondheat pump) that are thermally coupled together by an intermediate heatexchanger (i.e., a heat exchanger). In the intermediate heat exchanger,the working fluid in the bottoming heat pump 402 rejects heat to theworking fluid in the topping heat pump 404. Then, in a steam generator(i.e., a heat exchanger) the working fluid of the topping heat pump 404rejects heat to a third working fluid 408. In some instances, the steamgeneration system 400 may also include a steam compressor (not shown inFIG. 4 ), which is configured to increase the temperature and pressureof the third working fluid 408 after the third working fluid 408 absorbsheat from steam generator.

Each of the heat pumps 402, 404 are used to “pump” lower temperatureheat to a higher temperature by using an electrical energy source.Currently available heat pumps either do not generate a large enoughtemperature lift to produce steam or they require the use of a highertemperature waste heat stream as the energy source. As described herein,the system 400 utilizes a “cascading” or series of heat pump cycles inthermal connection with each other that progressively raise thetemperatures to deliver decarbonized steam at a lower cost thanalternative sources. The system 400 does not require waste heat todeliver high temperature steam.

The steam generation system 400 of FIG. 4 may be generally applicable toa variety of industrial processes and/or manufacturing environments. Forexample, the steam generation system 400 may be used to generateindustrial steam. In one instance, the bottoming heat pump 402 and thetopping heat pump 404 may be modular, electric-powered air-source heatpumps arranged in a thermally cascading manner. This modularity mayenable industry-specific needs, such as different steam pressures andcapacities. While the systems in this application illustrate two heatpump cycles (i.e., topping heat pump and bottoming heat pump), thesystem is scalable and can be modified to include additional heat pumps.In certain instances, the system may include three heat pump cycles. Incertain instances, the system may include four heat pump cycles. Incertain instances, the system may include five heat pump cycles. In oneinstance, the steam generation system 400 may generate steam at atemperature of approximately 150-degrees Celsius and at a pressure ofapproximately 4.5 bar, which may satisfy a majority of industrial steamproduction needs including the food, paper, and chemical industries.

In the steam generation system 400 of FIG. 4 , the bottoming heat pump402 may utilize ambient air as a heat source (i.e., air sourced). Theevaporator (i.e., heat exchanger) of the bottoming heat pump 402captures heat from the ambient air. The heat is absorbed by theevaporator of the bottoming heat pump 402, thereby evaporating theworking fluid within the bottoming heat pump 402.

The topping heat pump 404 is thermally coupled to the bottoming heatpump 402 by an intermediate heat exchanger. In one instance, theintermediate heat exchanger comprises the condenser of the bottomingheat pump 402 and the evaporator of the topping heat pump 404. Thus,within the intermediate heat exchanger, the condenser of the bottomingheat pump 402 rejects heat and the evaporator of the topping heat pump404 absorbs heat.

The conduit (i.e., pipe providing the fluid flow path) for a thirdworking fluid 408 is coupled to the topping heat pump 404 by a steamgenerator (i.e., heat exchanger). In one instance, the steam generatorcomprises the condenser of the topping heat pump 404 and the conduit fora third working fluid 408. Thus, within the steam generator, thecondenser of the topping heat pump 404 rejects heat and the thirdworking fluid 108 absorbs heat.

Before entering the steam generator, a mechanical pump may be used toincrease the pressure of the third working fluid 408. After the thirdworking fluid 408 exits the steam generator, a steam compressor may beused to increase the pressure and the temperature of the third workingfluid 408. Thus, a mechanical pump may be installed before the steamgenerator, a steam compressor may be installed after the steamgenerator, or both.

In one instance, the third working fluid 408 is water. Within the steamgenerator, the water absorbs heat from the working fluid of the toppingheat pump 404. In one example, the pressure of the water may be greaterthan or equal to the target steam saturation temperature. In otherwords, the water may absorb sufficient heat from the topping heat pump404 to evaporate into steam 410. After the steam generator, a steamcompressor may be used to directly increase the pressure and temperatureof the steam 410. In one example, the pressure of the water may be lessthan the target steam saturation temperature after exiting the steamgenerator and, therefore, the steam compressor may be used to increasethe pressure of the water to the required saturation temperature. Thesystem 400 may be retrofitted to existing steam generation systemswithin facilities. Alternatively, the system 400 may include a steamgeneration system as part of the overall system 400.

The steam generation system 400 may be powered by electricity 412. Inother words, electricity 412 is input into the steam generation system400 in order to generate steam 410. For example, the steam generationsystem 400 may be powered through grid electricity, onsite renewableenergy, or a combination thereof. The steam generation system 400 mayenable economic decarbonization of industrial steam production, as steamenergy in the industrial sector accounts for almost 4 quads of U.S.primary energy consumption and emits more than 200 MMtonne of CO2 everyyear.

In some instances, the steam generation system 400 may incorporateenergy arbitrage as described in reference to FIG. 1 . In other words,energy arbitrage may be used in conjunction with the steam generationsystem 400 by incorporating additional systems that can provide heatingto the steam generation system 400 and/or provide electricity to theheat pump systems described herein. The additional systems could includesolar arrays, thermal storage systems, and fuel boilers (e.g., naturalgas, coal, waste products, or biomass), among other systems. Thesesystems can be coupled to the steam generation system 400 and/or theheat pump systems and selectively actuated to provide heat to the system400 and/or electricity to the heat pump systems. The specific systemthat provides heat to the steam generation system 400 and/or electricityto the heat pump systems can be determined by the availability, andprice of the energy source of the system applying heat or electricity,as well as other factors including the requirements of the steamgeneration system 400. By incorporating energy arbitrage, the steamgeneration system 400 is capable of generating consistent steam deliverywhile significantly reducing carbon emissions.

In some instances, the steam generation system 400 may include more thantwo heat pumps arranged in a thermal cascading manner to heat pump airto generate steam. In one instance, the steam generation system 400 mayinclude three heat pumps. For example, the steam generation system 400may include a bottoming heat pump (i.e., a first heat pump), anintermediate heat pump (i.e., a second heat pump), and a topping heatpump (i.e., a third heat pump). In another instance, the steamgeneration system 400 may include four heat pumps. For example, thesteam generation system 400 may include a bottoming heat pump (i.e., afirst heat pump), a first intermediate heat pump (i.e., a second heatpump), a second intermediate heat pump (i.e., a third heat pump), and atopping heat pump (i.e., a fourth heat pump). In another instance, thesteam generation system 400 may include five heat pumps.

In one instance, the bottoming heat pump 402 is coupled to the ambientair (i.e., air sourced). However, in other instances, the bottoming heatpump 402 may be coupled to another low temperature heat source. Forexample, the low temperature heat source could be a liquid loop thatrejects heat to the air, the ground, or another co-located cooling load.In one example, the liquid loop may contain water.

FIG. 5 illustrates a partial diagram of a steam generation system 500,which is a partial embodiment of the steam generation system 400illustrated in FIG. 4 . The steam generation system 500 includes abottoming heat pump 502 (i.e., a first heat pump) and a topping heatpump 504 (i.e., a second heat pump) arranged in a thermally cascadingmanner. The bottoming heat pump 502 may be a low temperature air sourceheat pump and the topping heat pump 504 may be a high temperature steamcoupled heat pump. The steam generation system 500 may also include asteam compressor (not shown in FIG. 5 ).

The steam generation system 500 may include cascading heat pumps thatincorporate high-efficiency components to achieves a coefficient ofperformance greater than two without using waste heat. For example,high-efficiency components may include high-efficiency refrigerantcompressors and motors. In one instance, the compressors may be equal toor greater than 85% efficient and the motors may be equal to or greaterthan 93% efficient.

For example, a 1 thermal megawatt (MWth) steam generation system 500 mayproduce 150-degree Celsius steam at a nominal ambient temperature of20-degrees Celsius. In other words, the steam generation system 500 mayprovide a temperature lift from 20-degrees Celsius to 150-degreesCelsius at a coefficient of performance greater than two withoutrequiring waste heat.

Heat transfer 516 a involves the bottoming heat pump 502 capturing heatfrom the ambient air by evaporating a working fluid, which may be arefrigerant. In one instance, the ambient air may be approximately20-degrees Celsius, and the working fluid may be evaporated at15-degrees Celsius. Electricity 212 a may be applied to the bottomingheat pump 502, which may include a 88.5 kilowatt-electric (kWe) highefficiency compressor and motor. In one instance, the compressor power297 a may consume 75.5 kilowatts (kw). In one instance, the fan powerand losses 299 a may be 13 kWe.

Heat transfer 516 b involves the condenser from the bottoming heat pump502 rejecting heat to the evaporator in the topping heat pump 504,thereby evaporating the working fluid in the topping heat pump 504. Theworking fluid in the topping heat pump 504 may be a refrigerant. In oneinstance, the working fluid in the topping heat pump 504 may beevaporated at 60-degrees Celsius. Electricity 212 b may be applied tothe topping heat pump 504, which may include a 159.2 kWe high efficiencycompressor and motor. In one instance, the compressor power 297 b mayconsume 146 kw. In one instance, the fan power and losses 299 b may be13.2 kWe.

Heat transfer 516 c involves the condenser from the topping heat pump504 rejecting heat to an evaporating water stream. Thus, 1 MWth of steamis delivered at a 150-degrees Celsius saturation temperature.

FIG. 6 is a table outlining an exemplary design specification for atwo-stage compressor for the bottom cycle 602 of the steam generationsystem 600, which is a partial embodiment of the steam generation system500 illustrated in FIG. 5 . This compressor will be further shown anddescribed with reference to the first heat pump cycle 1002 of the steamgeneration system 100 of FIG. 10 . In one instance, the compressor inthe bottom cycle 602 may comprise two-stage compression with a singleshaft and motor. In other words, the first-stage of the compressor maycomprise a first compressor 638 and the second-stage of the compressormay comprise a second compressor 629. In one instance, a motor may turna shaft that drives both the first compressor 638 and the secondcompressor 629 (i.e., the compressors are rotatably coupled together ona shafter and powered by the same motor) (shown subsequently in FIG. 10). The specific speed (N_(s)) of the compressor versus the specificdiameter (D_(s)) of the compressor may result in an efficiency equal toor greater than 80% efficient. The total electrical efficiency may beapproximately 94.1% efficient.

FIG. 7 is a diagram of a design for a two-stage compressor for thetopping cycle 704 of the steam generation system 700, which is a partialembodiment of the steam generation system 400 illustrated in FIG. 4 . Inone instance, the compressors may comprise two-stage compression withtwo shafts and motors. In other words, the first-stage of the compressormay comprise a first compressor 774 and the second-stage of thecompressor may comprise a second compressor 763. In one instance, afirst motor may turn a shaft that drives the first compressor 774, and asecond motor may turn a separate shaft that drives the second compressor763 (i.e., the compressors are on separate shafts that are powered byseparate motors). This type of compressor is shown and described inreference to FIG. 10 .

The separate stages may reduce windage losses in the compressor motor.Moreover, the separate stages may isolate the higher risk components.For example, the second compressor 763 is a higher temperaturecompressor, which may create heightened risks. Thus, separating thesecond compressor 763 by providing a separate motor and shaft from thefirst compressor 774 may isolate the rest of the steam generation system700 from these challenges.

In one instance, the working fluid in the topping cycle 704 may enterthe first compressor 774 (i.e., at the inlet) at a temperature 716 d ofapproximately 103-degrees Celsius. The first compressor 774 compressesthe working fluid, which increases the temperature and pressure of theworking fluid. The working fluid may exit the first compressor 774(i.e., at the outlet) at a temperature 716 e of approximately144-degrees Celsius. The temperature 716 f of the working fluid from theeconomizer (which is shown and described in reference to FIG. 10 ) maybe approximately 104-degrees Celsius. The two streams of the workingfluid (which are at different temperatures) mix together, so that thetemperature of the working fluid may enter the second compressor 763(i.e., at the inlet) at a temperature 716 g of approximately 132-degreesCelsius. The second compressor 763 compresses the working fluid, whichincreases the temperature and pressure of the working fluid. The workingfluid may exit the second compressor 763 (i.e., at the outlet) at atemperature 716 h of approximately 174-degrees Celsius.

FIG. 8 is a table outlining an exemplary design specification for atwo-stage compressor for the topping cycle 804 of the steam generationsystem 800, which is a partial embodiment of the steam generation system700 illustrated in FIG. 7 . Such a compressor design can be seen andimplemented in the system 1000 of FIG. 10 in the topping heat pump cycle1004. Continuing with FIG. 8 , in one instance, the compressor in thetopping cycle 804 may comprise two-stage compression with two shafts andmotors. In other words, the first-stage of the compressor may comprise afirst compressor 874 and the second-stage of the compressor may comprisea second compressor 863. In one instance, a first motor may turn a shaftthat drives the first compressor 874, and a second motor may turn aseparate shaft that drives the second compressor 863 (i.e., thecompressors use different shafts and motors). The specific speed (N_(s))of the compressor versus the specific diameter (D_(s)) of the compressormay result in an efficiency equal to or greater than 80% efficient.

FIG. 9 is a diagram of the electric power input and thermal power outputof the steam generation system 900, which is a partial embodiment of thesteam generation system 400 illustrated in FIG. 4 . The steam generationsystem 900 comprises a bottoming heat pump 902 and a topping heat pump904. The electric power input may comprise electricity 912, which may beapproximately 0.5 megawatt-electric (MWe). The thermal power output maycomprise steam 910, which may be approximately 1.0 thermal megawatt(MWth) of steam 910 that is delivered at a 150-degrees Celsiussaturation temperature.

FIG. 10 illustrates a steam generation system 1000 including many of theelements described in reference to FIGS. 4 through 9 . FIG. 10 is adiagrammatic view of the steam generation system 1000, which includes afirst heat pump cycle 1002 (i.e., a bottoming heat pump cycle) and asecond heat pump cycle 1004 (i.e., a topping heat pump cycle) in thermalcommunication with each other. The steam generation system 1000 may alsoinclude a steam compressor (not shown in FIG. 10 ) that is in thermalcommunication with the second heat pump cycle 1004.

The first heat pump cycle 1002 circulates a first working fluid 1018 viaa conduit 1020 of the first heat pump cycle 1002, as illustrated in FIG.10 . In one instance, the first working fluid 1018 may be afluorocarbon. As nonlimiting examples, the fluorocarbon may beR1234ze(z) or R1234ze(E). In one instance, the first working fluid 1018may be a hydrofluoroolefin. As a nonlimiting example, thehydrofluoroolefin may be R514a. In one instance, the first working fluid1018 may be a hydrofluoroether. In one instance, the first working fluid1018 may be a hydrocarbon. In one instance, the first working fluid 1018may be carbon dioxide. In one instance, the first working fluid 1018 maybe ammonia. In one instance, the first working fluid 1018 may be water.In one instance, the first working fluid 1018 may be an engineeredfluid. As a nonlimiting example, the engineered fluid may be Novec 649.

In the first heat pump cycle 1002, a heat exchanger 1022 receives thefirst working fluid 1018 from an expansion valve 1024. In other words,the first working fluid 1018 exits the expansion valve 1024 at theexpansion valve outlet 1026 and enters the heat exchanger 1022 at theheat exchanger inlet 1028. A conduit 1020 connects the expansion valveoutlet 1026 to the heat exchanger inlet 1028, thereby establishing fluidcommunication between the expansion valve 1024 and the heat exchanger1022. In the heat exchanger 1022, the first working fluid 1018 absorbsheat. This heat absorption may vaporize the first working fluid 1018,whereby the first working fluid 1018 is a low-pressure vapor when itexits the heat exchanger 1022 at the heat exchanger outlet 1030. In oneinstance, the heat exchanger 1022 may include the evaporator of thefirst heat pump cycle 1002, whereby the evaporator absorbs heat and thefirst working fluid 1018 is evaporated within the evaporator. In oneinstance, the heat exchanger 1022 may be a low-temperature evaporator.In one instance, the heat exchanger 1022 may operate at an efficiencygreater than or equal to 90%.

A compressor 1038 receives the first working fluid 1018 from the heatexchanger 1022. In other words, the first working fluid 1018 exits theheat exchanger 1022 at the heat exchanger outlet 1030 and enters thecompressor 1038 at the compressor inlet 1040. A conduit 1020 connectsthe heat exchanger outlet 1030 to the compressor inlet 1040, therebyestablishing fluid communication between the heat exchanger 1022 and thecompressor 1038. In the compressor 1038, the first working fluid 1018 iscompressed to a higher pressure, which increases the temperature, beforethe first working fluid 1018 exits the compressor 1038 at the compressoroutlet 1042. Thus, the low-pressure vapor is compressed to a higherpressure. In one instance, the first working fluid 1018 is a mediumpressure fluid when it exits the compressor 1038 at the compressoroutlet 1042. In one instance, the compressor 1038 is a high-efficiencycompressor. In one instance, the compressor 1038 may be a centrifugalcompressor. In one instance, the compressor 1038 may be a two-stagecentrifugal compressor. In one instance, the compressor 1038 may beelectrically powered. A motor 1027 may turn a shaft that drives thecompressor 1038. In one instance, the motor 1027 may be a high-speedand/or high-efficiency motor. In one instance, the motor 1027 may beelectrically powered.

In one instance, the first heat pump cycle 1002 does not include asuction-line heat exchanger (“SLHX”). However, in other instances, aSLHX (which is not shown in the first heat pump cycle 1002 of FIG. 10 )may be incorporated into the first heat pump cycle 1002. In anembodiment of the first heat pump cycle 1002 with a SLHX, the SLHXreceives the first working fluid 1018 from the heat exchanger 1022 in afirst passage of the SLHX. In other words, the first working fluid 1018exits the heat exchanger 1022 at the heat exchanger outlet 1030 andenters the SLHX at the SLHX inlet. A conduit connects the heat exchangeroutlet 1030 to the SLHX inlet, thereby establishing fluid communicationbetween the heat exchanger 1022 and the SLHX. In the first passage ofthe SLHX, the first working fluid 1018 absorbs heat, thereby furtherheating (i.e., preheating) the first working fluid 1018 before it exitsthe SLHX at the SLHX outlet. Then, the first working fluid 1018 exitsthe SLHX at the SLHX outlet and enters the compressor 1038 at thecompressor inlet 1040. A conduit connects the SLHX outlet to thecompressor inlet 1040, thereby establishing fluid communication betweenthe SLHX and the compressor 1038.

Continuing on with a description of the first heat pump cycle 1002 asshown in FIG. 10 , a second compressor 1029 receives the first workingfluid 1018 from the compressor 1038. In other words, the first workingfluid 1018 exits the compressor 1038 at the compressor outlet 1042 andenters the second compressor 1029 at the second compressor inlet 1031. Aconduit 1020 connects the compressor outlet 1042 to the secondcompressor inlet 1031, thereby establishing fluid communication betweenthe compressor 1038 and the second compressor 1029.

In certain instances, the first heat pump cycle 1002 may alternativelynot include a second compressor 1029. That is, the first heat pump cycle1002 may only include a single compressor 1038. In such an instance, theheat exchanger 1044 receives the first working fluid 1018 from thecompressor 1038. More particularly, the first working fluid 1018 exitsthe compressor 1038 at the compressor outlet 1042 and enters the heatexchanger 1044 at the heat exchanger inlet 1046. The conduit connectsthe compressor outlet 1042 to the heat exchanger inlet 1046, therebyestablishing fluid communication between the compressor 1038 and theheat exchanger 1044.

Continuing on with the first heat pump cycle 1002 as shown in FIG. 10 ,the first working fluid 1018 is compressed to a higher pressure by thesecond compressor 1029, which increases the temperature, before thefirst working fluid 1018 exits the second compressor 1029 at the secondcompressor outlet 1033. In one instance, the second compressor 1029 is ahigh-efficiency compressor. In one instance, the second compressor 1029may be a centrifugal compressor. In one instance, the second compressor1029 may be electrically powered. A motor 1027 may turn a shaft thatdrives the second compressor 1029. In one instance, the motor 1027 maybe a high-speed and/or high-efficiency motor. In one instance, the motor1027 may be electrically powered. In one instance, the motor 1027 mayturn a shaft that drives both the compressor 1038 and the secondcompressor 1029 (i.e., the compressors use the same shaft and motor). Inanother instance, the motor 1027 turns a shaft that drives thecompressor 1038 and a second motor (i.e., a separate motor not shown inFIG. 10 ) turns a separate shaft that drives the second compressor 1029(i.e., the compressors use a different motor and a different shaft).Exemplary design specification for the compressors are shown in FIG. 6 .

A heat exchanger 1044 (i.e., the intermediate heat exchanger) thermallycouples the first heat pump cycle 1002 with the second heat pump cycle1004. In one instance, the heat exchanger 1044 receives the firstworking fluid 1018 from the second compressor 1029. In other words, thefirst working fluid 1018 exits the second compressor 1029 at the secondcompressor outlet 1033 and enters the heat exchanger 1044 at the heatexchanger inlet 1046. A conduit 1020 connects the second compressoroutlet 1033 to the heat exchanger inlet 1046, thereby establishing fluidcommunication between the second compressor 1029 and the heat exchanger1044. In other instances, when the first heat pump cycle 1002 does notinclude a second compressor 1029, the heat exchanger 1044 receives thefirst working fluid 1018 from the compressor 1038, as described above.

In the heat exchanger 1044, the first working fluid 1018 rejects heat.This heat rejection may condense the first working fluid 1018 before itexits the heat exchanger 1044 at the heat exchanger outlet 1048. In oneinstance, the heat exchanger 1044 comprises the condenser of the firstheat pump cycle 1002 and the evaporator of the second heat pump cycle1004. Thus, within the heat exchanger 1044, the condenser of the firstheat pump cycle 1002 rejects heat and the evaporator of the second heatpump cycle 1004 absorbs heat. In the heat exchanger 1044, the secondworking fluid 1050, which circulates within a conduit 1052 within thesecond heat pump cycle 1004, absorbs heat. This heat absorption mayvaporize the second working fluid 1050, whereby the second working fluid1050 is a low-pressure vapor when it exits the heat exchanger 1044. Inone instance, the heat exchanger 1044 may operate at an efficiencygreater than or equal to 90%.

Still referring to the first heat pump cycle 1002, an economizer 1035(i.e., a heat exchanger) may be incorporated into the cycle 1002. Whenthe first heat pump cycle 1002 includes the economizer 1035, the fluidstream of the first working fluid 1018 from the heat exchanger 1044splits into a primary fluid stream and a secondary fluid stream. Withinthe economizer 1035, the primary fluid stream of the first working fluid1018 rejects heat and the secondary fluid stream of the first workingfluid 1018 absorbs heat.

In the primary fluid stream, the economizer 1035 receives the firstworking fluid 1018 from the heat exchanger 1044 in a first passage ofthe economizer 1035. In other words, the first working fluid 1018 exitsthe heat exchanger 1044 at the heat exchanger outlet 1048 and enters theeconomizer 1035 at an economizer inlet 1037. The conduit 1020 connectsthe heat exchanger outlet 1048 to the economizer inlet 1037, therebyestablishing fluid communication between the heat exchanger 1044 and theeconomizer 1035. In the first passage of the economizer 1035, the firstworking fluid 1018 rejects heat, thereby cooling the first working fluid1018 before it exits the economizer 1035 at the economizer outlet 1039.

In the secondary fluid stream, an expansion valve 1041 receives thefirst working fluid 1018 from the heat exchanger 1044. In other words,the first working fluid 1018 exits the heat exchanger 1044 at the heatexchanger outlet 1048 and enters the expansion valve 1041 at theexpansion valve inlet 1043. The conduit 1020 connects the heat exchangeroutlet 1048 to the expansion valve inlet 1043, thereby establishingfluid communication between the heat exchanger 1044 and the expansionvalve 1041. In the expansion valve 1041, the first working fluid 1018 isexpanded to a lower pressure (i.e., the pressure is reduced), whichdecreases the temperature, before the first working fluid 1018 exits theexpansion valve 1041 at the expansion valve outlet 1045. In oneinstance, the first working fluid 1018 may partially vaporize, wherebythe first working fluid 1018 become a two-phase fluid in the expansionvalve 1041.

In the secondary fluid stream, the economizer 1035 receives the firstworking fluid 1018 from the expansion valve 1041 in a second passage ofthe economizer 1035. In other words, the first working fluid 1018 exitsthe expansion valve 1041 at the expansion valve outlet 1045 and entersthe economizer 1035 at an economizer inlet 1047. The conduit 1020connects the expansion valve outlet 1045 to the economizer inlet 1047,thereby establishing fluid communication between the expansion valve1041 and the economizer 1035. In the second passage of the economizer1035, the first working fluid 1018 absorbs heat, thereby heating thefirst working fluid 1018 before it exits the economizer 1035 at theeconomizer outlet 1049. In one instance, in which the first workingfluid 1018 is a two-phase fluid, the heat absorption increases the vaporquality of the two-phase fluid.

In the secondary fluid stream, the second compressor 1029 may receivethe first working fluid 1018 from the second passage of the economizer1035. In other words, the first working fluid 1018 exits the economizer1035 at the economizer outlet 1049 and enters the second compressor 1029at the second compressor inlet 1031. A conduit 1020 connects theeconomizer outlet 1049 to the second compressor inlet 1031, therebyestablishing fluid communication between the economizer 1035 and thesecond compressor 1029. In some instances, the conduit 1020 carrying thefirst working fluid 1018 from the economizer outlet 1049 (i.e., theconduit 1020 exiting the second passage of the economizer 1035) maymerge with the conduit 1020 carrying the first working fluid 1018 fromthe compressor outlet 1042 (i.e., the conduit 1020 exiting thecompressor 1038), thereby merging two separate fluid streams (i.e., bothfluids being the first working fluid 1018) before entering the secondcompressor 1029. In one instance, the first working fluid 1018 withinthe conduit 1020 from the economizer outlet 1049 may be a two-phasefluid stream and the first working fluid 1018 within the conduit 1020from the compressor outlet 1042 may be a medium pressure fluid. Thetwo-phase fluid stream (i.e., the first working fluid 1018 exiting theeconomizer outlet 1049) may be a lower temperature and an approximatelyequivalent pressure to the medium pressure fluid (i.e., the firstworking fluid 1018 exiting the compressor outlet 1042). Thus, when thetwo fluid streams merge, thereby mixing the two fluids, the two-phasefluid stream may cool the medium pressure fluid stream, therebydecreasing the specific work of the second compressor 1029 and improvingthe overall efficiency of the steam generation system 1000.

In such an instance when the first heat pump cycle 1002 does not includea second compressor 1029, the compressor 1038 may receive the firstworking fluid 1018 from the economizer 1035. In other words, the firstworking fluid 1018 exits the economizer 1035 at the economizer outlet1049 and enters the compressor 1038 at the compressor inlet 1040. Aconduit connects the economizer outlet 1049 to the compressor inlet1040, thereby establishing fluid communication between the economizer1035 and the compressor 1038.

In other instances, the first heat pump cycle 1002 does not include aneconomizer 1035. In such an instance, the expansion valve 1024 receivesthe first working fluid 1018 from the heat exchanger 1044. In otherwords, the first working fluid 1018 exits the heat exchanger 1044 at theheat exchanger outlet 1048 and enters the expansion valve 1024 at theexpansion valve inlet 1058. A conduit 1020 connects the heat exchangeroutlet 1048 to the expansion valve inlet 1058, thereby establishingfluid communication between the heat exchanger 1044 and the expansionvalve 1024.

In one instance, an expansion valve 1024 receives the first workingfluid 1018 from the economizer 1035. In other words, the first workingfluid 1018 exits the economizer 1035 at the economizer outlet 1039 andenters the expansion valve 1024 at the expansion valve inlet 1058. Aconduit 1020 connects the economizer outlet 1039 to the expansion valveinlet 1058, thereby establishing fluid communication between theeconomizer 1035 and the expansion valve 1024. In other instances, whenthe first heat pump cycle 1002 does not include an economizer 1035, theexpansion valve 1024 receives the first working fluid 1018 from the heatexchanger 1044, as described above. In the expansion valve 1024, thefirst working fluid 1018 is expanded to a lower pressure, whichdecreases the temperature, before the first working fluid 1018 exits theexpansion valve 31024 at the expansion valve outlet 1026.

In one instance, such as shown in FIG. 10 , the first heat pump cycle1002 does not include a SLHX. However, in other instances, a SLHX isincorporated into the first heat pump cycle 1002. In such an instance,the SLHX receives the first working fluid 1018 from the economizer 1035in a second passage of the SLHX. In other words, the first working fluid1018 exits the economizer 1035 at the economizer outlet 1039 and entersthe SLHX at the SLHX inlet. A conduit connects the economizer outlet1039 to the SLHX inlet, thereby establishing fluid communication betweenthe economizer 1035 and the SLHX. In the second passage of the SLHX, thefirst working fluid 1018 rejects heat, thereby cooling (i.e.,precooling) the first working fluid 1018 before it exits the SLHX at theSLHX outlet. This precooling of the first working fluid 1018 may lowerthe vapor quality of the first working fluid 1018 before the firstworking fluid 1018 enters the heat exchanger 1022 at the heat exchangerinlet 1028 and may increase the amount of latent heat transfer that canoccur. Then, the first working fluid 1018 exits the SLHX at the SLHXoutlet and enters the expansion valve 1024 at the expansion valve inlet1058. A conduit 1020 connects the SLHX outlet to the expansion valveinlet 1058, thereby establishing fluid communication between the SLHXand the expansion valve 1024.

In one instance, the first heat pump cycle 1002 includes a SLHX, butdoes not include an economizer 1035. Therefore, the fluid stream of thefirst working fluid 1018 does not split into a primary fluid stream anda secondary fluid stream. Accordingly, because there is not a secondaryfluid stream, there is not an expansion valve 1041 associated with asecondary fluid stream. In other words, the first working fluid 1018exits the heat exchanger 1044 at the heat exchanger outlet 1048 andenters the SLHX at the SLHX inlet. A conduit 1020 connects the heatexchanger outlet 1048 to the SLHX inlet, thereby establishing fluidcommunication between the heat exchanger 1044 and the SLHX. Then, thefirst working fluid 1018 exits the SLHX at the SLHX outlet and entersthe expansion valve 1024 at the expansion valve inlet 1058. A conduit1020 connects the SLHX outlet to the expansion valve inlet 1058, therebyestablishing fluid communication between the SLHX and the expansionvalve 1024.

Turning to the second heat pump cycle 1004 of FIG. 10 , the second heatpump cycle 1004 circulates a second working fluid 1050. In one instance,the second working fluid 1050 may be a fluorocarbon. As nonlimitingexamples, the fluorocarbon may be R1234ze(z) or R1234ze(E). In oneinstance, the second working fluid 1050 may be a hydrofluoroolefin. As anonlimiting example, the hydrofluoroolefin may be R514a. In oneinstance, the second working fluid 1050 may be a hydrofluoroether. Inone instance, the second working fluid 1050 may be a hydrocarbon. In oneinstance, the second working fluid 1050 may be carbon dioxide. In oneinstance, the second working fluid 1050 may be ammonia. In one instance,the second working fluid 1050 may be water. In one instance, the secondworking fluid 1050 may be an engineered fluid. As a nonlimiting example,the engineered fluid may be Novec 649.

In one instance, the same fluid may be used for both the first workingfluid 1018 and the second working fluid 1050. In other instances, adifferent fluid may be used for the first working fluid 1018 and thesecond working fluid 1050.

In one instance, the second heat pump cycle 1004 may contain the samecomponents as the first heat pump cycle 1002. The components of thesecond heat pump cycle 1004 may be arranged in the same configuration asthe components of the first heat pump cycle 1002. The components of thesecond heat pump cycle 1004 may be arranged in a different configurationthan the components of the first heat pump cycle 1002. In otherinstances, the second heat pump cycle 1004 may contain differentcomponents than the first heat pump cycle 1002.

In the second heat pump cycle 1004, the heat exchanger 1044 receives thesecond working fluid 1050 from an expansion valve 1060. In other words,the second working fluid 1050 exits the expansion valve 1060 at theexpansion valve outlet 1062 and enters the heat exchanger 1044 at theheat exchanger inlet 1064. A conduit 1052 connects the expansion valveoutlet 1062 to the heat exchanger inlet 1064, thereby establishing fluidcommunication between the expansion valve 1060 and the heat exchanger1044. In the heat exchanger 1044, the second working fluid 1050 absorbsheat from the first working fluid 1018 of the first heat pump cycle1002. This heat absorption may vaporize the second working fluid 1050,whereby the second working fluid 1050 is a low-pressure vapor when itexits the heat exchanger 1044 at the heat exchanger outlet 1066. In oneinstance, the heat exchanger 1044 comprises the condenser of the firstheat pump cycle 1002 and the evaporator of the second heat pump cycle1004. Thus, within the heat exchanger 1044, the condenser of the firstheat pump cycle 1002 rejects heat and the evaporator of the second heatpump cycle 1004 absorbs heat. In one instance, the heat exchanger 1044may operate at an efficiency greater than or equal to 90%.

In one instance, a suction-line heat exchanger (“SLHX”) 1068 may beincorporated into the second heat pump cycle 1004, as seen in FIG. 10 .The SLHX 1068 receives the second working fluid 1050 from the heatexchanger 1044 in a first passage of the SLHX 1068. In other words, thesecond working fluid 1050 exits the heat exchanger 1044 at the heatexchanger outlet 1066 and enters the SLHX 1068 at the SLHX inlet 1070. Aconduit 1052 connects the heat exchanger outlet 1066 to the SLHX inlet1070, thereby establishing fluid communication between the heatexchanger 1044 and the SLHX 1068. In the first passage of the SLHX 1068,the second working fluid 1050 absorbs heat, thereby further heating(i.e., preheating) the second working fluid 1050 before it exits theSLHX 1068 at the SLHX outlet 1072. Then, the second working fluid 1050exits the SLHX 1068 at the SLHX outlet 1072 and enters the compressor1074 at the compressor inlet 1076. A conduit connects the SLHX outlet1072 to the compressor inlet 1076, thereby establishing fluidcommunication between the SLHX 1068 and the compressor 1074.

In other instances, the second heat pump cycle 1004 does not include theSLHX 1068. In other words, the second working fluid 1050 exits the heatexchanger 1044 at the heat exchanger outlet 1066 and enters thecompressor 1074 at the compressor inlet 1076. A conduit 1052 connectsthe heat exchanger outlet 1066 to the compressor inlet 1076, therebyestablishing fluid communication between the heat exchanger 1044 and thecompressor 1074.

Continuing on with the second heat pump cycle 1004 shown in FIG. 10 , acompressor 1074 receives the second working fluid 1050 from the SLHX1068. In other words, the second working fluid 1050 exits the SLHX 1068at the SLHX outlet 1072 and enters the compressor 1074 at the compressorinlet 1076. A conduit 1052 connects the SLHX outlet 1072 to thecompressor inlet 1076, thereby establishing fluid communication betweenthe SLHX 1068 and the compressor 1074. In the compressor 1074, thesecond working fluid 1050 is compressed to a higher pressure, whichincreases the temperature, before the second working fluid 1050 exitsthe compressor 1074 at the compressor outlet 1078. Thus, thelow-pressure vapor is compressed to a higher pressure. In one instance,the second working fluid 1050 is a medium pressure fluid when it exitsthe compressor 1074 at the compressor outlet 1078. In one instance, thecompressor 1074 is a high-efficiency compressor. In one instance, thecompressor 1074 may be a centrifugal compressor. In one instance, thecompressor 1074 may be a two-stage centrifugal compressor. In oneinstance, the compressor 1074 may be electrically powered. A motor 1061may turn a shaft that drives the compressor 1074. In one instance, themotor 1061 may be a high-speed and/or high-efficiency motor. In oneinstance, the motor 1061 may be electrically powered.

In one instance, a second compressor 1063 may be incorporated into thesecond heat pump cycle 1004 as shown in FIG. 10 . The second compressor1063 receives the second working fluid 1050 from the compressor 1074. Inother words, the second working fluid 1050 exits the compressor 1074 atthe compressor outlet 1078 and enters the second compressor 1063 at thesecond compressor inlet 1065. A conduit 1052 connects the compressoroutlet 1078 to the second compressor inlet 1065, thereby establishingfluid communication between the compressor 1074 and the secondcompressor 1063. In other instances, the second heat pump cycle 1004does not include a second compressor 1063. Thus, the heat exchanger 1080receives the second working fluid 1050 from the compressor 1074. Inother words, the second working fluid 1050 exits the compressor 1074 atthe compressor outlet 1078 and enters the heat exchanger 1080 at theheat exchanger inlet 1082. A conduit connects the compressor outlet 1078to the heat exchanger inlet 1082, thereby establishing fluidcommunication between the compressor 1074 and the heat exchanger 1080.

In the second compressor 1063, the second working fluid 1050 iscompressed to a higher pressure, which increases the temperature, beforethe second working fluid 1050 exits the second compressor 1063 at thesecond compressor outlet 1067. In one instance, the second compressor1063 is a high-efficiency compressor. In one instance, the secondcompressor 1063 may be a centrifugal compressor. In one instance, thesecond compressor 1063 may be electrically powered. A motor 1069 mayturn a shaft that drives the second compressor 1063. In one instance,the motor 1069 may be a high-speed and/or high-efficiency motor. In oneinstance, the motor 1069 may be electrically powered. In one instance,the motor 1061 may turn a shaft that drives the compressor 1074 and themotor 1069 may turn a separate shaft that drives the second compressor1063 (i.e., the compressors use a different motor and shaft). In anotherinstance, one motor (either motor 1061 or motor 1069) may turn a shaftthat drives both the compressor 1074 and the second compressor 1063(i.e., the compressors use the same motor and shaft). Exemplary designspecification for the compressors can be seen in FIG. 8 .

A heat exchanger 1080 thermally couples the second heat pump cycle 1004with a third working fluid 1008. In one instance, the heat exchanger1080 receives the second working fluid 1050 from the second compressor1063. In other words, the second working fluid 1050 exits the secondcompressor 1063 at the second compressor outlet 1067 and enters the heatexchanger 1080 at the heat exchanger inlet 1082. A conduit 1052 connectsthe second compressor outlet 1067 to the heat exchanger inlet 1082,thereby establishing fluid communication between the second compressor1063 and the heat exchanger 1080. In other instances, when the secondheat pump cycle 1004 does not include a second compressor 1063, the heatexchanger 1080 receives the second working fluid 1050 from thecompressor 1074, as described above.

In the heat exchanger 1080, the second working fluid 1050 rejects heat.This heat rejection may condense the second working fluid 1050 before itexits the heat exchanger 1080 at the heat exchanger outlet 1084. In oneinstance, the heat exchanger 1080 may be the condenser of the secondheat pump cycle 1004, whereby the condenser rejects heat and the secondworking fluid 1050 condenses within the condenser. In the heat exchanger1080, the third working fluid 1008, which may flow within a conduit,absorbs heat. This heat absorption may vaporize the third working fluid1008, whereby the third working fluid 1008 is steam when it exits theheat exchanger 1080. In one instance, the heat exchanger 1080 mayoperate at an efficiency greater than or equal to 90%. The third workingfluid 1008 may flow through a system that further includes a pump andcompressor, as illustrated in FIG. 3 .

In one instance, as seen in FIG. 10 , an economizer 1071 (i.e., a heatexchanger) may be incorporated into the second heat pump cycle 1004.When the second heat pump cycle 1004 includes the economizer 1071, thefluid stream of the second working fluid 1050 splits into a primaryfluid stream and a secondary fluid stream. Within the economizer 1071,the primary fluid stream of the second working fluid 1050 rejects heatand the secondary fluid stream of the second working fluid 1050 absorbsheat.

In the primary fluid stream, the economizer 1071 receives the secondworking fluid 1050 from the heat exchanger 1080 in a first passage ofthe economizer 1071. In other words, the second working fluid 1050 exitsthe heat exchanger 1080 at the heat exchanger outlet 1084 and enters theeconomizer 1071 at an economizer inlet 1073. A conduit 1052 connects theheat exchanger outlet 1084 to the economizer inlet 1073, therebyestablishing fluid communication between the heat exchanger 1080 and theeconomizer 1071. In the first passage of the economizer 1071, the secondworking fluid 1050 rejects heat, thereby cooling the second workingfluid 1050 before it exits the economizer 1071 at the economizer outlet1075.

In the secondary fluid stream, an expansion valve 1077 receives thesecond working fluid 1050 from the heat exchanger 1080. In other words,the second working fluid 1050 exits the heat exchanger 1080 at the heatexchanger outlet 1084 and enters the expansion valve 1077 at theexpansion valve inlet 1079. A conduit 1052 connects the heat exchangeroutlet 1084 to the expansion valve inlet 1079, thereby establishingfluid communication between the heat exchanger 1080 and the expansionvalve 1077. In the expansion valve 1077, the second working fluid 1050is expanded to a lower pressure (i.e., the pressure is reduced), whichdecreases the temperature, before the second working fluid 1050 exitsthe expansion valve 1077 at the expansion valve outlet 1081. In oneinstance, the second working fluid 1050 may partially vaporize, wherebythe second working fluid 1050 become a two-phase fluid in the expansionvalve 1077.

In the secondary fluid stream, the economizer 1071 receives the secondworking fluid 1050 from the expansion valve 1077 in a second passage ofthe economizer 1071. In other words, the second working fluid 1050 exitsthe expansion valve 1077 at the expansion valve outlet 1081 and entersthe economizer 1071 at an economizer inlet 1083. A conduit 1052 connectsthe expansion valve outlet 1081 to the economizer inlet 1083, therebyestablishing fluid communication between the expansion valve 1077 andthe economizer 1071. In the second passage of the economizer 1071, thesecond working fluid 1050 absorbs heat, thereby heating the secondworking fluid 1050 before it exits the economizer 1071 at the economizeroutlet 1085. In one instance, in which the second working fluid 1050 isa two-phase fluid, the heat absorption increases the vapor quality ofthe two-phase fluid.

In the secondary fluid stream, the second compressor 1063 may receivethe second working fluid 1050 from the second passage of the economizer1071. In other words, the second working fluid 1050 exits the economizer1071 at the economizer outlet 1085 and enters the second compressor 1063at the second compressor inlet 1065. A conduit 1052 connects theeconomizer outlet 1085 to the second compressor inlet 1065, therebyestablishing fluid communication between the economizer 1071 and thesecond compressor 1063. In some instances, the conduit 1052 carrying thesecond working fluid 1050 from the economizer outlet 1085 (i.e., theconduit 1052 exiting the second passage of the economizer 1071) maymerge with the conduit 1052 carrying the second working fluid 1050 fromthe compressor outlet 1078 (i.e., the conduit 1052 exiting thecompressor 1074), thereby merging two separate fluid streams (i.e., bothfluids being the second working fluid 1050) before entering the secondcompressor 1063. In one instance, the second working fluid 1050 withinthe conduit 1052 from the economizer outlet 1085 may be a two-phasefluid stream and the second working fluid 1050 within the conduit 1052from the compressor outlet 1078 may be a medium pressure fluid. Thetwo-phase fluid stream (i.e., the second working fluid 1050 exiting theeconomizer outlet 1085) may be a lower temperature and an approximatelyequivalent pressure to the medium pressure fluid (i.e., the secondworking fluid 1050 exiting the compressor outlet 1078). Thus, when thetwo fluid streams merge, thereby mixing the two fluids, the two-phasefluid stream may cool the medium pressure fluid stream, therebydecreasing the specific work of the second compressor 1063 and improvingthe overall efficiency of the steam generation system 1000.

In such instances when the second heat pump cycle 1004 does not includea second compressor 1063, the compressor 1074 may receive the secondworking fluid 1050 from the economizer 1071. In other words, the secondworking fluid 1050 exits the economizer 1071 at the economizer outlet1085 and enters the compressor 1074 at the compressor inlet 1076. Aconduit connects the economizer outlet 1085 to the compressor inlet1076, thereby establishing fluid communication between the economizer1071 and the compressor 1074.

In such instances when the SLHX 1068 is incorporated into the secondheat pump cycle 1004 (such as seen in FIG. 10 ), the SLHX 1068 receivesthe second working fluid 1050 from the heat exchanger 1080 in a secondpassage of the SLHX 1068. In other words, the second working fluid 1050exits the heat exchanger 1080 at the heat exchanger outlet 1084 andenters the SLHX 1068 at the SLHX inlet 1088. A conduit 1052 connects theheat exchanger outlet 1084 to the SLHX inlet 1088, thereby establishingfluid communication between the heat exchanger 1080 and the SLHX 1068.In the second passage of the SLHX 1068, the second working fluid 1050rejects heat, thereby cooling (i.e., precooling) the second workingfluid 1050 before it exits the SLHX 1068 at the SLHX outlet 1090. Thisprecooling of the second working fluid 1050 may lower the vapor qualityof the second working fluid 1050 before the second working fluid 1050enters the heat exchanger 1022 at the heat exchanger inlet 1028 and mayincrease the amount of latent heat transfer that can occur. Then, thesecond working fluid 1050 exits the SLHX 1068 at the SLHX outlet 1090and enters the expansion valve 1060 at the expansion valve inlet 1092. Aconduit 1052 connects the SLHX outlet 1090 to the expansion valve inlet1092, thereby establishing fluid communication between the SLHX 1068 andthe expansion valve 1060.

In such instances when the second heat pump cycle 1004 does not includethe SLHX 1068, the second working fluid 1050 exits the economizer 1071at the economizer outlet 1075 and enters the expansion valve 1060 at theexpansion valve inlet 1092. A conduit 1052 connects the economizeroutlet 1075 to the expansion valve inlet 1092, thereby establishingfluid communication between the economizer 1071 and the expansion valve1060.

In other instances, the second heat pump cycle 1004 includes a SLHX1068, but does not include an economizer 1071. Therefore, the fluidstream of the second working fluid 1050 does not split into a primaryfluid stream and a secondary fluid stream. Accordingly, because there isnot a secondary fluid stream, there is not an expansion valve 1077associated with a secondary fluid stream. In other words, the secondworking fluid 1050 exits the heat exchanger 1080 at the heat exchangeroutlet 1084 and enters the SLHX 1068 at the SLHX inlet 1088. A conduit1052 connects the heat exchanger outlet 1084 to the SLHX inlet 1088,thereby establishing fluid communication between the heat exchanger 1080and the SLHX 1068. Then, the second working fluid 1050 exits the SLHX1068 at the SLHX outlet 1090 and enters the expansion valve 1060 at theexpansion valve inlet 1092. A conduit 1052 connects the SLHX outlet 1090to the expansion valve inlet 1092, thereby establishing fluidcommunication between the SLHX 1068 and the expansion valve 1060.

In other instances, the second heat pump cycle 1004 does not include aneconomizer 1071 and does not include a SLHX 1068. Thus, the expansionvalve 1060 receives the second working fluid 1050 from the heatexchanger 1080. In other words, the second working fluid 1050 exits theheat exchanger 1080 at the heat exchanger outlet 1084 and enters theexpansion valve 1060 at the expansion valve inlet 1092. A conduit 1052connects the heat exchanger outlet 1084 to the expansion valve inlet1092, thereby establishing fluid communication between the heatexchanger 1080 and the expansion valve 1060.

In one instance, an expansion valve 1060 receives the second workingfluid 1050 from the SLHX 1068. In other words, the second working fluid1050 exits the SLHX 1068 at the SLHX outlet 1090 and enters theexpansion valve 1060 at the expansion valve inlet 1092. A conduit 1052connects the SLHX outlet 1090 to the expansion valve inlet 1092, therebyestablishing fluid communication between the SLHX 1068 and the expansionvalve 1060. In other instances, when the second heat pump cycle 1004does not include a SLHX 1068, the expansion valve 1060 receives thesecond working fluid from the economizer 1071, as described above. Inanother instance, when the second heat pump cycle 1004 does not includean economizer 1071 and does not include a SLHX 1068, the expansion valve1060 receives the second working fluid 1050 from the heat exchanger1080, as described above. In the expansion valve 1060, the secondworking fluid 1050 is expanded to a lower pressure, which decreases thetemperature, before the second working fluid 1050 exits the expansionvalve 1060 at the expansion valve outlet 1062.

A third working fluid 1008 may absorb heat from the heat exchanger 1080,as illustrated in FIG. 10 . In other words, the heat exchanger 1080 mayreceive the third working fluid 1008. Within the heat exchanger 1080,the second working fluid 1050 rejects heat and the third working fluid1008 absorbs heat. In one instance, the heat exchanger 1080 may includethe condenser of the second heat pump cycle 1004, whereby the condenserrejects heat and the third working fluid 1008 absorbs heat. The secondworking fluid 1050 is condensed as it rejects heat within the condenser.In one instance, the heat exchanger 1080 may be a steam generator.Within the steam generator, the third working fluid 1008 may absorbsufficient heat to vaporize.

In one instance, the third working fluid 1008 may be supplied to theheat exchanger 1080 via a conduit (not shown in FIG. 10 ). In otherwords, the conduit for the third working fluid 1008 is coupled to thesecond heat pump cycle 1004 by the heat exchanger 1080.

In one instance, a mechanical pump (not shown in FIG. 10 ) may increasethe pressure of the third working fluid 1008. A similar embodiment ofthe pump 301 is shown in FIG. 3 . The mechanical pump may be upstreamfrom the heat exchanger 1080, whereby the heat exchanger 1080 receivesthe third working fluid 1008 from the mechanical pump. In other words,the third working fluid 1008 exits the mechanical pump at the mechanicalpump outlet and enters the heat exchanger 1080 at a heat exchangerinlet. A conduit connects the mechanical pump outlet to the heatexchanger inlet, thereby establishing fluid communication between themechanical pump and the heat exchanger 1080. The third working fluid1008 exits the heat exchanger 1080 at a heat exchanger outlet and mayenter a conduit.

In one instance, a steam compressor (not shown in FIG. 10 ) may increasethe pressure and temperature of the third working fluid 1008. A similarembodiment of the steam compressor 306 can be seen in FIG. 3 . The steamcompressor may be downstream from the heat exchanger 1080, whereby thesteam compressor receives the third working fluid 1008 from the heatexchanger 1080. In other words, the third working fluid 1008 exits theheat exchanger 1080 at the heat exchanger outlet and enters the steamcompressor at the steam compressor inlet. A conduit connects the heatexchanger outlet to the steam compressor inlet, thereby establishingfluid communication between the heat exchanger 1080 and the steamcompressor.

In the steam compressor, the third working fluid 1008 is compressed to ahigher pressure and temperature. In one instance, the steam compressorincreases the pressure and temperature of the third working fluid 1008to turn the third working fluid 1008 into steam before the third workingfluid 1008 exits the steam compressor at the steam compressor outlet.The steam may enter a conduit connected to the steam compressor outlet.In one instance, the steam compressor delivers steam at a temperatureequal to or greater than 120 degrees Celsius. In one instance, the steamcompressor is a high-efficiency compressor. In one instance, the steamcompressor may be a centrifugal compressor. In one instance, the steamcompressor may be electrically powered.

In one instance, the third working fluid 1008 is water. Within the heatexchanger 1080, the water absorbs heat from the second working fluid1050 of the second heat pump cycle 1004. In one example, the pressure ofthe water may be greater than or equal to the target steam saturationtemperature when the water exits the heat exchanger 1080 at the heatexchanger outlet. In other words, the water may absorb sufficient heatfrom the second heat pump cycle 1004 to evaporate into steam. After theheat exchanger 1080, a steam compressor may be used to directly increasethe pressure and temperature of the steam. In one example, the pressureof the water may be less than the target steam saturation temperaturewhen the water exits the heat exchanger 1080 at the heat exchangeroutlet. Therefore, the steam compressor may be used to increase thepressure of the water to the required saturation temperature.

Referring back to the first heat pump cycle 1002 of FIG. 10 , a transferfluid 1013 may reject heat to the heat exchanger 1022. In other words,the heat exchanger 1022 receives the transfer fluid 1013. Within theheat exchanger 1022, the transfer fluid 1013 rejects heat and the firstworking fluid 1018 absorbs heat. In one instance, the heat exchanger1022 may include the evaporator of the first heat pump cycle 1002,whereby the transfer fluid 1013 rejects heat, and the evaporator absorbsheat. The first working fluid 1018 is evaporated as it absorbs heatwithin the evaporator. In one instance, the heat exchanger 1022 may be alow-temperature evaporator.

In one instance, the transfer fluid 1013 may be supplied to the heatexchanger 1022 via a conduit (not shown in FIG. 10 ). In other words,the conduit for the transfer fluid 1013 is coupled to the first heatpump cycle 1002 by the heat exchanger 1022.

In one instance, a mechanical pump (not shown in FIG. 10 ) may increasethe pressure of the transfer fluid 1013. The mechanical pump may beupstream from the heat exchanger 1022, whereby the heat exchanger 1022receives the transfer fluid 1013 from the mechanical pump. In otherwords, the transfer fluid 1013 exits the mechanical pump at themechanical pump outlet and enters the heat exchanger 1022 at a heatexchanger inlet. A conduit connects the mechanical pump outlet to theheat exchanger inlet, thereby establishing fluid communication betweenthe mechanical pump and the heat exchanger 1022. The transfer fluid 1013exits the heat exchanger 1022 at a heat exchanger outlet and may enter aconduit.

In one instance, the transfer fluid 1013 is ambient air, whereby theheat exchanger 1022 of the first heat pump cycle 1002 utilizes ambientair as a heat source (i.e., air sourced). The heat exchanger 1022 of thefirst heat pump cycle 1002 may capture heat from the ambient air. Theheat is absorbed by the heat exchanger 1022 of the first heat pump cycle1002, thereby evaporating the first working fluid 1018 within the firstheat pump cycle 1002.

In other instances, the transfer fluid 1013 may be liquid that isconnected to a low temperature heat source. In one instance, the lowtemperature heat source may be ambient air. In other instances, thefirst heat pump cycle 1002 may be coupled to another low temperatureheat source. For example, the low temperature heat source could be aliquid loop that rejects heat to the air, the ground, or anotherco-located cooling load. In one example, the liquid loop may containwater.

The heat generation system of FIG. 10 may additionally include a controlsystem in electrical communication with the first heat pump cycle 1002and the second heat pump cycle 1004. The control system may control thedelivery of heat from a first heat source and/or a second heat source tothe third working fluid 1008. The first heat source may include thefirst heat pump cycle 1002 and the second heat pump cycle 1004. Thesecond heat source may include an alternate heat source such as thermalstorage units which are heated via renewable energy sources (e.g., solararrays). Additionally or alternatively, the control system may controlthe source of electrical power that is supplied to the first and secondheat pump cycles 1002, 1004. The electrical power may be selectivelysupplied by the electrical grid or a renewable energy source.

To this end, reference is made to FIG. 11 , which is a diagram of anenergy arbitrage system 1100 incorporating a cascading heat pump system1102 (such as the first and second heat pump cycles 1002 and 1004 fromFIG. 10 or the first and second heat pump cycles 302 and 304 of FIG. 3 )for steam production. The energy arbitrage system 1100 includes multiplethermal energy sources for supplying heat in order to generate steam forindustrial applications, among other uses. Additionally, oralternatively, one or more of the thermal energy sources may supply thesteam as opposed to supplying heat for a central steam productionsystem.

In one instance, the energy arbitrage system 1100 includes a renewableenergy source 1104, which may be a solar array or grid that is inelectrical communication with the electric grid 1106. The electric grid1106 is in electrical communication with and capable of powering thecascading heat pump system 1102. The cascading heat pump system 1102 isalso in electrical communication with the renewable energy source 1104,which is capable of supplying power thereto. The renewable energy source1104 is coupled to an energy storage system 1108 such as a thermalenergy storage system capable of storing energy in the form of heat. Thethermal storage system 1108 may include one or more storage vesselscapable of storing a heated fluid (e.g., steam). The energy storagesystem 1108 may be an electrical storage unit such as one or morebatteries which are able to supply electricity to the cascading heatpump system 1102.

The energy arbitrage system 1100 may also include a boiler 1110, such asa natural gas boiler. The boiler 1110 however may be a different type ofboiler such as one burning coal, a biomass, waste products, or anothersuitable fuel. Each of the boiler 1110, the cascading heat pump system1102, the renewable energy source 1104, and the energy storage system1108 may be electrically controlled by the control system 1112. Thecontrol system 1112 may control the delivery of either steam and/or heatto an industrial application. In an instance, each of the boiler 1110,the cascading heat pump system 1102, and the energy storage system 1108(when configured as a thermal energy storage unit) deliver steam 1114for use in an industrial application, or for another use. In such aninstance, the boiler 1110 is capable of deliver steam 1114 when actuatedby the control system 1112, the cascading heat pump system 1102(including steam generation components such as the pump 301, the heatexchanger 380, and the steam compressor 306) are capable of deliveringsteam 1114 when actuated by the control system 1112, and the energystorage system 1108 is capable of delivering steam 1114 when actuated bythe control system 1112. The energy arbitrage system 1110 may functionwithout a control system 1112, and, as such, be controlled manually.

The control system 1112 may utilize the following exemplary parametersin the arbitrage system 1000 to determine which system(s) to operate ata given time. The parameters include but are not limited to renewableelectricity generation (kW and kWh), thermal storage capacity or energystored (kW and kWh), steam output per device (e.g. heat pump, boiler,thermal storage), facility steam demand (steam mass or volume flow ratesand steam pressure), and utility prices (e.g., PPA rate, gridelectricity rate structure, and fuel prices), among other factors. Thecontrol system 1112 can measure steam mass, volume flow rates, and steampressure coming from the various sources. The control system 1112 canalso selectively turn on and off the various energy sources of thearbitrage system 1100 based on the parameters listed above, amongothers.

The control system 1112 may calculate system performance using thefollowing metrics: steam output divided by electricity input=heat pumpefficiency, and steam output divided by natural gas input=boilerefficiency. These metrics may be used to determine whether it is moreeconomical to operate the heat pump, boiler, or other systems. Utilityprices, including PPA rate, grid electricity rate structure, and fuelprices, may be used as factors when considering which system to utilizeto provide steam. The energy arbitrage system 1110 can be used toefficiently and cost-effectively deliver steam by selectively deliveringsteam from one or more of the energy input sources. The energy arbitragesystem 1110 is capable of maximizing decarbonization in the steamproduction process.

The following includes a list of exemplary embodiments of the energyarbitrage system 1110. Conventionally, industrial steam 1114 isgenerated from a boiler (e.g., natural gas boiler) 1110. There is noarbitrage in this configuration as steam is provided by one source onlyand there is no ability to alter the energy source input.

A first form of arbitrage using the energy arbitrage system 1100 is toprovide steam 1114 only via renewable energy sources 1104 that utilize athermal storage system 1108. That is, there is no boiler in thisconfiguration. While the energy is supplied by renewable sources, thisis an expensive decarbonization option.

A second form of arbitrage using the energy arbitrage system 1100 is toselectively provide steam 1114 from one or both of a boiler 1110 and acascading heat pump system 1102 which is supplied electricity from arenewable energy source 1104.

The control system is in communication with the renewable energy source1104 (kWh generated). In this instance, all electricity generated issent to the heat pump 1102. The control system 1112 can monitor thesteam output (e.g., flow rate and pressure) of the heat pump 1102 andthe steam demand from the facility (e.g., flow rate and pressure). Thecontrol system 1102 can communicate with the boiler 1110 to generate theremainder of the steam required by the facility. The steam output of theboiler 1110 can also be measured (e.g., flow rate and pressure) by thecontrol system 1112.

A third form of arbitrage using the energy arbitrage system 1100 is toprovide steam 1114 from one or both of a boiler 1110 and a cascadingheat pump system 1102 which is supplied electricity from a renewableenergy source 1104. In this configuration, the renewable energy source1104 also provides electricity to the electric grid 1106 when the supplyof electricity exceeds the demands of the cascading heat pump system1102.

In this configuration, there may be excess electricity from therenewable energy sources 1104. This excess electricity can be suppliedto the grid 1106, which in turn can provide credit for demands on theelectric grid 1106 (e.g., for supplying electricity to the heat pumpsystem 1102). In this configuration, the control system 1112 may monitorthe facility steam demand and the steam output of the heat pump 1102. Ifthe steam output of the heat pump 1102 delivers the entire facilitydemand, then the control system 1102 communicates with the renewableenergy source 1104 and excess electricity is diverted to the grid 1106(net-metering). At times when the renewable energy source 1104 does notproduce sufficient electricity to the heat pumps 1102, the controlsystem 1112 will communicate with the boiler 1110 to provide theremaining steam required for the facility. The control system 1112 maydetermine the most economically efficient fuel source (electricity fromthe grid versus fuel for the boiler) given the current energy costs ofelectricity and fuel, respectively.

A fourth form of arbitrage using the energy arbitrage system 1100 is toprovide steam 1114 from only the cascading heat pump system 1102 whichis supplied electricity from a renewable energy source 1104. In thisconfiguration, the renewable energy source 1104 also provideselectricity to the electric grid 1106 when the supply of electricityexceeds the demands of the cascading heat pump system 1102. The boileris not used in this configuration. As with the third form of arbitrage,in the fourth form of arbitrage, excess electricity produced fromrenewable energy sources can be diverted to the grid 1106. In this case,the control system 1112 receives the steam demands from the facility asan input. All of the steam, in this form of arbitrage, is going to beprovided by the cascading heat pump system 1102, and the control system1112 will selectively determine the source of electrical power to theheat pump system 1102. If the renewable energy source 1104 is capable ofproviding all of the electricity needs for the heat pump system 1102,then the heat pump system 1102 will not draw any electricity from thegrid 1106. If there is excess electricity produced from the renewableenergy source 1104, then the excess will be sent to the grid 1106 (netmetering). If the electricity needs of the heat pump system 1102 greaterthan the amount that can be produced by the renewable energy source1104, then the control system 1112 will utilize as much renewable energy1104 as possible and the remainder of electricity will be pulled fromthe grid 1106.

In this form, the system 1100 may include a boiler 1110. If therenewable energy sources 1104 do not provide excess electricity, thecontrol system 1112 may communicate with the grid 1106 to pull gridelectricity to power the heat pump 1102 instead of signaling the boiler1110 to deliver steam 1114. This may occur if the control system 1112determines that the heat pump 1102 operating with a portion ofelectricity from the grid 1106 is more economical than operating the gasboiler 1110.

A fifth form of arbitrage using the energy arbitrage system 1100 is toprovide steam 1114 from one or both of the cascading heat pump system1102 which is supplied electricity from a renewable energy source 1104and the energy storage system 1108 connected to the renewable energysource 1104. This configuration avoids grid demand charges and yieldscomplete decarbonization. The grid and gas boiler are not utilized inthis configuration. The control system 1112 may monitor steam outputfrom the heat pump system 1102, steam demand of the facility, andrenewable electricity generation at the renewable energy source 1104.

If the heat pump system 1102 provides complete steam demands for thefacility and there is excess electricity from renewable energy sources,then electricity may be diverted to the energy storage device 1108 tocharge the device (e.g., energy storage unit, thermal storage unit)(measures the charge/capacity of the device). If there is not excesselectricity from the renewable energy sources 1104, then the controlsystem 1112 may communicate with the energy storage device 1108 todischarge heat/steam 1114 to meet the facility steam demand incombination with the heat pump 1102.

If the energy storage device is fully charged, and there is still excesselectricity, then electricity would be diverted to the grid 1106.

Having the energy arbitrage system 1110 include renewable energy sources1104 that are connected to the electrical grid 1106 enables the systemto use net metering, which is an electric grid billing mechanism where auser is charged for the difference of the cost of energy pulled from thegrid (consumed) and the cost of energy sent to the grid (generated).

The following is a description of an exemplary computer 1200 that ispart of or useable with the energy arbitrage system 1110 describedherein. FIG. 12 illustrates an example of a suitable computing andnetworking environment 1200 that may be used to implement variousaspects of the present disclosure described herein, such as the controlsystem 1112 of FIG. 11 . As illustrated in FIG. 12 , the computing andnetworking environment 1200 includes a general purpose computing device1200, although it is contemplated that the networking environment 1200may include other computing systems, such as smart phones, servercomputers, hand-held or laptop devices, tablet devices, multiprocessorsystems, microprocessor-based systems, set top boxes, programmableconsumer electronic devices, network PCs, minicomputers, mainframecomputers, digital signal processors, state machines, logic circuitries,distributed computing environments that include any of the abovecomputing systems or devices, and the like.

Components of the computer 1200 may include various hardware components,such as a processing unit 1202, a data storage 1204 (e.g., a systemmemory), and a system bus 1206 that couples various system components ofthe computer 1200 to the processing unit 1202. The system bus 1206 maybe any of several types of bus structures including a memory bus ormemory controller, a peripheral bus, and a local bus using any of avariety of bus architectures. For example, such architectures mayinclude Industry Standard Architecture (ISA) bus, Micro ChannelArchitecture (MCA) bus, Enhanced ISA (EISA) bus, Video ElectronicsStandards Association (VESA) local bus, and Peripheral ComponentInterconnect (PCI) bus also known as Mezzanine bus.

The computer 1200 may further include a variety of computer-readablemedia 1208 that includes removable/non-removable media andvolatile/nonvolatile media, but excludes transitory propagated signals.Computer-readable media 1208 may also include computer storage media andcommunication media. Computer storage media includesremovable/non-removable media and volatile/nonvolatile media implementedin any method or technology for storage of information, such ascomputer-readable instructions, data structures, program modules orother data, such as RAM, ROM, EEPROM, flash memory or other memorytechnology, CD-ROM, digital versatile disks (DVD) or other optical diskstorage, magnetic cassettes, magnetic tape, magnetic disk storage orother magnetic storage devices, or any other medium that may be used tostore the desired information/data and which may be accessed by thecomputer 1200. Communication media includes computer-readableinstructions, data structures, program modules or other data in amodulated data signal such as a carrier wave or other transportmechanism and includes any information delivery media. The term“modulated data signal” means a signal that has one or more of itscharacteristics set or changed in such a manner as to encode informationin the signal. For example, communication media may include wired mediasuch as a wired network or direct-wired connection and wireless mediasuch as acoustic, RF, infrared, and/or other wireless media, or somecombination thereof. Computer-readable media may be embodied as acomputer program product, such as software stored on computer storagemedia.

The data storage or system memory 1204 includes computer storage mediain the form of volatile/nonvolatile memory such as read only memory(ROM) and random access memory (RAM). A basic input/output system(BIOS), containing the basic routines that help to transfer informationbetween elements within the computer 1200 (e.g., during start-up) istypically stored in ROM. RAM typically contains data and/or programmodules that are immediately accessible to and/or presently beingoperated on by processing unit 1202. For example, in one embodiment,data storage 1204 holds an operating system, application programs, andother program modules and program data.

Data storage 1204 may also include other removable/non-removable,volatile/nonvolatile computer storage media. For example, data storage1204 may be: a hard disk drive that reads from or writes tonon-removable, nonvolatile magnetic media; a magnetic disk drive thatreads from or writes to a removable, nonvolatile magnetic disk; and/oran optical disk drive that reads from or writes to a removable,nonvolatile optical disk such as a CD-ROM or other optical media. Otherremovable/non-removable, volatile/nonvolatile computer storage media mayinclude magnetic tape cassettes, flash memory cards, digital versatiledisks, digital video tape, solid state RAM, solid state ROM, and thelike. The drives and their associated computer storage media, describedabove and illustrated in FIG. 12 , provide storage of computer-readableinstructions, data structures, program modules and other data for thecomputer 1200.

A user may enter commands and information through a user interface 1210or other input devices such as a tablet, electronic digitizer, amicrophone, keyboard, and/or pointing device, commonly referred to asmouse, trackball or touch pad. The commands and information may be forsetting up the lighting and/or watering schedules, including thespecific parameters of each. Other input devices may include a joystick,game pad, satellite dish, scanner, or the like. Additionally, voiceinputs, gesture inputs (e.g., via hands or fingers), or other naturaluser interfaces may also be used with the appropriate input devices,such as a microphone, camera, tablet, touch pad, glove, or other sensor.These and other input devices are often connected to the processing unit1202 through a user interface 1210 that is coupled to the system bus1206, but may be connected by other interface and bus structures, suchas a parallel port, game port or a universal serial bus (USB). A monitor1212 or other type of display device is also connected to the system bus1206 via an interface, such as a video interface. The monitor 1212 mayalso be integrated with a touch-screen panel or the like.

When the computer 1200 is operating as a control system 1112, there maybe various inputs and outputs associated with the energy arbitragesystem 1100 of FIG. 11 . For instance, the computer 1200 may includevarious inputs associated with the facility steam requirements, steamoutputs from the boiler 1110, steam outputs from the heat pump cycles1102, and steam outputs from the thermal storage units 1108. Additionalinputs may include electricity production from the renewable energysource 1104, and the outflow from the renewable energy source includingto the grid 1106, to the heat pump 1102, and to the thermal storageunits 1108. Additional inputs can also include the electricityrequirements of the heat pump system 1102 and the amount of electricitybeing supplied from the grid 1106. The computer 1200 may be inelectrical communication with each of the heat pump system 1102,renewable energy source 1104, the thermal storage units 1108 so thecomputer 1200 can actuate a component of the system 1100 to operatebased on the various inputs received. In this way, the communicationwith the various systems can also be outputs so the computer 1200 cancontrol the operation thereof.

The computer 1200 may operate in a networked or cloud-computingenvironment using logical connections of a network interface or adapter1214 to one or more remote devices, such as a remote computer. Theremote computer may be a personal computer, a server, a router, anetwork PC, a peer device or other common network node, and typicallyincludes many or all of the elements described above relative to thecomputer 1200. The logical connections depicted in FIG. 12 include oneor more local area networks (LAN) and one or more wide area networks(WAN), but may also include other networks. Such networking environmentsare commonplace in offices, enterprise-wide computer networks, intranetsand the Internet.

When used in a networked or cloud-computing environment, the computer1200 may be connected to a public and/or private network through thenetwork interface or adapter 1214. In such embodiments, a modem or othermeans for establishing communications over the network is connected tothe system bus 1206 via the network interface or adapter 1214 or otherappropriate mechanism. A wireless networking component including aninterface and antenna may be coupled through a suitable device such asan access point or peer computer to a network. In a networkedenvironment, program modules depicted relative to the computer 1200, orportions thereof, may be stored in the remote memory storage device.

The foregoing merely illustrates the principles of the invention.Various modifications and alterations to the described embodiments willbe apparent to those skilled in the art in view of the teachings herein.It will thus be appreciated that those skilled in the art will be ableto devise numerous systems, arrangements and methods which, although notexplicitly shown or described herein, embody the principles of theinvention and are thus within the spirit and scope of the presentinvention. From the above description and drawings, it will beunderstood by those of ordinary skill in the art that the particularembodiments shown and described are for purposes of illustrations onlyand are not intended to limit the scope of the present invention.References to details of particular embodiments are not intended tolimit the scope of the invention.

What is claimed is:
 1. A system for generating steam, said system comprising: one or more heat pump cycles configured to transfer heat from an ambient air source via one or more working fluids, to add energy to a feed stream comprising water to generate an output stream comprising said steam at a saturation temperature of at least 120 degrees Celsius.
 2. The system of claim 1, further comprising a heat exchanger located within a heat pump cycle of said one or more heat pump cycles, wherein said heat exchanger is configured to preheat a working fluid of said one or more working fluids prior to compressing said working fluid downstream of a condenser.
 3. The system of claim 2, wherein said heat exchanger is a suction-line heat exchanger in fluid communication between at least two sections of said heat pump cycle, wherein said at least two sections are at different temperatures.
 4. The system of claim 1, further comprising said one or more working fluids, wherein said one or more working fluids comprises at least one of a fluorocarbon, a hydrofluoroolefin, a hydrofluoroether, a hydrocarbon, carbon dioxide, ammonia, or water.
 5. The system of claim 1, wherein at least one heat pump cycle of said one or more heat pump cycles comprises one or more compressors.
 6. The system of claim 5, wherein said one or more compressors comprises a centrifugal compressor.
 7. The system of claim 5, wherein at least one compressor of said one or more compressors is electrically powered.
 8. The system of claim 5, wherein at least one compressor of said one or more compressors is a double ended compressor with one or more compressor wheels on each side of said double ended compressor.
 9. The system of claim 1, wherein at least one heat pump cycle of said one or more heat pump cycles comprises an economizer.
 10. The system of claim 1, wherein said temperature of said steam is at least 150 degrees Celsius.
 11. The system of claim 1, wherein said temperature of said steam is between 120 degrees Celsius and 150 degrees Celsius.
 12. The system of claim 1, wherein a heat pump cycle of said one or more heat pump cycles comprises at least two compressors in series.
 13. The system of claim 1, wherein a heat pump cycle of said one or more heat pump cycles comprises at least two compressors in parallel.
 14. The system of claim 1, wherein a heat pump cycle of said one or more heat pump cycles comprises at least two compressors that are rotatably coupled together on a shaft.
 15. The system of claim 1, wherein a temperature of said ambient air source is less than or equal to 40 degrees Celsius.
 16. The system of claim 1, wherein said system comprises at least two heat pump cycles thermally coupled via at least a first heat exchanger, wherein a bottom heat pump cycle of said at least two heat pump cycles circulates a first working fluid through said first heat exchanger that condenses the first working fluid, a second heat exchanger, to transfer heat from an ambient air stream to a bottom cycle of said at least two heat pump cycles that evaporates the first working fluid, and wherein said top cycle circulates a second working fluid through said first heat exchanger to evaporate said second working fluid, a second compressor, and a third heat exchanger that condenses the second working fluid to transfer heat to a stream comprising water.
 17. The system of claim 1, further comprising a steam compressor to compress said stream comprising water downstream of said one or more heat pump cycles, wherein said steam compressor outputs superheated or saturated steam.
 18. The system of claim 17, wherein said steam exiting said one or more heat pump cycles has a saturation temperature less than 120 degrees Celsius, and said steam compressor increases said saturation temperature of said steam to at least 120 degrees Celsius.
 19. The system of claim 17, wherein said steam compressor is electrically powered.
 20. The system of claim 17, further comprising a second steam compressor in series with said steam compressor. 